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Frame Swap

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Jodell1979

Frame Swap

Well, we have started a frame swap for our 81 f150. I found a local 91 f250 that was cheap and had the running gear so we picked it up at a really good price. Currently we have it down to the frame and we have our truck bed and front fenders and radiator support off. Before we start anything else i have been reading a lot of the topics of the past builds and would like for anyone that has any forethought of things we need to look out for before we remount all this stuff to its new home. Amy advise would be appreciated.

1981 f-150 long bed 4x4
351W two tone dark over light brown

Gary Lewis

Re: Frame Swap

Administrator

The only thing I'm aware of that could cause a problem is the bumper mounting. But you might want to read the thread on Chassis Compatibility Question.

And particularly see Cory's post in that thread:

Rembrant wrote

I have a 1995 frame in my 1980 Flareside. The Bullnose front bumper swap has been done a few different ways, but I personally chopped the front ends of the 1995 frame off, and welded in Bullnose frame "horns" to mount the front bumper:

The only other issue I ran into was the very tail end of the frame only has one set of holes for the bed, and the Bullnose frame has two sets of holes (the second set is only for the "old" Flareside bed, which didn't exist in 1995). I drilled the extra two holes and bam, done.

There was also one small "flare" I will call in the 1995 rear most crossmember...I don't even know what it is for, but it interfered with the Flareside bed rear sill. I gave it a couple smacks with a hammer and made some clearance...haha...the frame, not the bed.

So my truck is a 1980 F150, with a 1986 300 inline six, sitting on a 1995 F150 chassis with the 1995 5spd, axles, differentials, etc.

Gary, AKA "Gary fellow": Profile

Dad's: '81 F150 Ranger XLT 4x4: Down for restomod: Full-roller "stroked 351M" w/Trick Flow heads & intake, EEC-V SEFI/E4OD/3.50 gears w/Kevlar clutches
Blue: 2015 F150 Platinum 4x4 SuperCrew wearing Blue Jeans & sporting a 3.5L EB & Max Tow
Big Blue: 1985 F250HD 4x4: 460/ZF5/3.55's, D60 w/Ox locker & 10.25 Sterling/Trutrac, Blue Top & Borgeson, & EEC-V MAF/SEFI

Jodell1979

Re: Frame Swap

I looked hard at the front end when purchasing it and the bricknose still had the shape but i will have to drill a hole at the top.

1981 f-150 long bed 4x4
351W two tone dark over light brown

Gary Lewis

Re: Frame Swap

Administrator

Sounds like you have it thought out.

Gary, AKA "Gary fellow": Profile

Rembrant

Re: Frame Swap

In reply to this post by Gary Lewis

Gary Lewis wrote

The only thing I'm aware of that could cause a problem is the bumper mounting. But you might want to read the thread on Chassis Compatibility Question.

And particularly see Cory's post in that thread:

He's all good with the 1991 frame Gary. They didn't switch to the boxed end crumble zone frame until 1992, so all the mods I did won't apply to him.

I don't know what differences exist between an F250 and an F150, if any...but the front bumper horns should be OK.

1994 F150 4x2 Flareside. 5.0 w/MAF, 4R70W, stock.
1984 F150 4X2 Flareside. Mild 302 w/ 5spd. Sold.
1980 F150 4X4 Flareside. 300i6 w/ 5spd. Sold in 2021.
1980 F100 4X2 Flareside. 351w/2bbl w/NP435. Sold in 1995

Gary Lewis

Re: Frame Swap

Administrator

Thanks, Cory!

Gary, AKA "Gary fellow": Profile

salans7

Re: Frame Swap

Looks like the original truck is a 351W, and the donor frame from the 1991 is from a diesel engine truck? If so, the engine crossmembers are different between small block and big block/diesel trucks. The 351W oil filter will normally come through a hole cut in the frame on the small block chassis. The oil filter may not clear the diesel/big block frame, so you may need to use an oil filter relocation kit with this new frame if your are keeping the 351W. I can't speak for certain on whether the oil filter will clear or not, I just know the crossmembers are different.