What seat base is this?

Good job Chris! Editing some photos now showing the underside of my 86 Supercab truck.

I took some measurements earlier today and while the parts trucks are filled with well, parts, from what I could tell the 83 Supercab with split bench has the same hole pattern as a full bench from an 85 F350 C&C (So regular cab). Could you flip your split bench over sometime and measure the dimensions between all the holes? I'll do the same with an 80 full bench  (from an 80 F350 C&C) I have in my shop.

I'll do that as soon as I get home.  It's already on its side in the garage, only way it would fit.

Taken from underneath a 1986 F250 4wd Supercab with captain's chairs.
Arrows point toward front of truck.
Note: I installed nuts (blue loctite) and washers on all but the Passenger Rear Inner (limited access). This is not factory procedure and was done for no real reason. These are factory locations and the captive nuts are beneath the "extra" nuts.

Driver - Front Outer


Driver - Front Inner


Driver - Rear Outer


Driver - Rear Inner (seatbelt bolt is large beveled square nut)


Passenger - Both Front and Rear Outer


Passenger - Both Front Inner and Outer (Inner partially beneath heat shield)


Passenger - Both Rear Inner and Outer (Outer partially seen in top right. Inner beneath heat shield)


Passenger - Rear Outer (note unused "nut" to the rear)

Ok, I went back under the truck and too some pictures to mimic the ones Scott took.

Front Driver Outer.  Looks like mine was tack welded at some point


Front Driver Inner.  For me this is just a dimple with no reinforcement.  The dimple isn't the exact hole location, but it's close.


Driver Rear Outer


Driver Rear Inner. Forgot to markup front is to the left.


Passenger Front Outer


Passenger Rear Outer.  Looks like my bench is using the 'spare' nut on Scotts picture.


Passenger Front Inner. Again, an unreinforced dimple.


Passenger Rear Inner  Very hard for me to get a shot of due to the heat shield.


I also took some pictures of the bench itself.



I tried to measure the bolt holes, front-rear was approx 15.5"


Rear left-right was approx 42 1/8"

Well done.

Not that's it's critical but I think the arrow on your Rear Driver Outer is pointing the wrong way.

I see that both Driver Outers are on the inside of that reinforcement strip whereas mine are on the outside. So even though the captain's chair fits in them they are technically too far in and might be why the dimples don't line up.

I didn't get to measure my 80 seat bottom this evening but your measurements are pretty much spot on with my measuring of the split and full benches still installed in the trucks.
I had front to back (bolt center to center) at 15.5" and longways (bolt center to center) at 42.25.
Makes sense that they'd be the same although it contradicts some of the posts I was reading last night. ?
We haven't check that the design is the same though even if the dimensions are. Perhaps there is a difference there.
I'll measure the 80 seat tomorrow afternoon.
Sorry, I know this doesn't help your plight at all. Just me getting caught up in it

Is there anything else I can get/measure for you? I don't know if the reinforcements could easily be popped off or not but I wouldn't be surprised if they could be since they are just there to spread the load.

It's entirely possible that I have that arrow wrong.  I'll have another look tomorrow.

I noticed that the bench bolts were on the other side of the strip.  I'll plop the driver seat in and line up the dimple to see where the others land.

I don't know how hard it would be, but if you could measure from the seat belt bolt to the driver side rear inner mount that would tell me how far out I am.

If the reinforcement is anything like the floor of my Samurai  it's heat welded or spot welded in place so it may not just pop off.  I don't know for certain though.  I also noticed that the reinforcement that your seats have is different from mine, maybe a 2wd 4x4 difference?

You bet - I'll measure that tomorrow.

I was assuming they are spot welded and even if so, you're right that they may not come off easily without damage. Another member on here (salans7 iirc) is going to reinforce his floor but I can't recall if he has identified an approach yet. I feel like we discussed adding cut out pieces from another truck and using panel adhesive between them.

Just looking over the pictures again.  On my truck all the bolt holes for the seat are reinforced, but this reinforcement is just an additional later of sheet metal.

On Scotts pictures, there are additional pieces used for reinforcement which appear to be heavier than just a single layer of additional sheet metal.  I am thinking that fender washers and maybe some automotive adhesive will be enough.  I can also make reinforcement strips out of 16GA sheet metal, it just sucks hack sawing it.

The only reinforcement part that will be even a little tricky is the driver side inner bolt.  The passenger ones will be hard too, unless the heat shield comes off easy.

CRittaler wrote

I don't know how hard it would be, but if you could measure from the seat belt bolt to the driver side rear inner mount that would tell me how far out I am.

3 7/8" Center to center

Awesome!  Thanks!  Looks like when I had it bolted up I measured around 2 5/8.  I'll line up with that and see how the rest looks!

That would seem to align with the inside vs outside of the reinforcement rail (driver outers).

Ducked outside again to take some measurements.  First I lined up the driver front mount with the dimple, then measured the inner rear offset from the seat belt.

Front point aligned with the dimple


Offset from seat belt bolt


Outer rear


Outer front


I then aligned the inner rear as best I could to Scotts measurement of 3 7/8" offset from the seatbelt and took pictures of the other mounting points

Offset from seat belt


Front inner.  Note it's not aligned with the dimple now.


Front outer


Rear outer



I would like to make some observations.  With both Scotts setting and aligning the front bolt with the dimples the seat appears to be slightly off center from the steering wheel, slightly outboard.  My shop is too small for me to be able to get a good picture through the front windshield but I will try tomorrow.

When the seat is setup using my factory bench holes it looks properly centered.  I don't know if this is an optical illusion or what.

I would also like to bring attention to the rectangular divots in the front and rear outer pictures.  These appear to be used for locating the additional reinforcement in Scotts pictures.

Scott, if it's not too much trouble, can you measure the offset of the outer bolts to the rectangular divots in the floor?  I'm assuming the carpet is out of the truck you've been measuring.

Sorry Chris - these photos have been from my 86 which is carpeted + heat/sound deadener. I was around my parts trucks today and crawled under the Supercabs but they both came with benches so don't really help with anything.

Regardless of lining up with the steering wheel, I see no reason not to use the two outers that line up. No reason to drill new holes if not necessary.

No worries!  I was going to use the holes that lined up anyways, I was just looking for completeness for our measurements to determine if there is a 3rd floor pan style.

I'm expecting my Noico sound deadening to come tomorrow, that's part of why I've been digging into this so much.  I don't want to have to put the busted bench (driver side doesn't fold) back in just to pull it out again.

From what I've been seeing, it looks like the only offset is the driver side outers being slightly inset from yours.  On the pictures of the passenger side the rear outers appear to be inline, left to right, but offset forward for the captains seats.  I'll verify this either later tonight or tomorrow.

Thanks again for the pictures!

Went ahead and drilled the holes.

For the driver side I used the factory outer bench holes, tightened the seat down and drilled some pilot holes before removing the seat and pushing the step drill through.

For the rear inner I'm going to have to get under the truck and notch the seatbelt brace so that I can clear the nut.  For the front I'll use a large fender washer probably glued in place with some automotive adhesive and a lock washer and nut.

Driver side rear inner.  Bolt catches the edge of the seatbelt bracket.


Driver side front inner.


For the passenger side the outer front lined up with the bracket.  The rear outer was directly in line with the factory bracket.

Offset on passenger side from the factory rear outer mount.


I couldn't get pictures of the other mounts from underneath because of the heat shields.  I'll have to figure out how they come off so I can get under there.  Might even have to take my welder out of the box and tack the nuts in place.

My next plan is to examine the driver side slider to see if it can be modified to slide further forward to allow easier access to the back.  I'm a tall fat guy and the passenger side was a very tight squeeze to get back there.