I just bought a Gear Vendors Unit !

Lovers of trucks,

After attempting to source a small block zf5 for some time and considering the costs to aquire and rebuild one along with the modifications I'd have to make that aren't easily reversable,  I have opted to add a GV unit to my F150. (the final overdrive ratio is nearly the same as the ZF 5th gear.)

I would like to perform the installation all in the same weekend. So, I'm looking for information on how to accurately get my driveshaft measurement in order to shorten one from a JY or order a new one that is the correct length.  I have asked GV for an advanced PDF copy of the install instructions.

Recommendations? Lessons learned from your install? Measurements of your unit behind a NP208?
Thoughts on driveline angle to the differential when adding approx 12" to the length of the transfer case and the truck is lifted 4"?

Also, how much of the installation should I document on this site?  Before/after RPM per gear data?

What say ye forum members?  What information would be valuable to you?

I was hoping for something more specific, but anything can be beneficial...

https://www.youtube.com/watch?v=qceslrlxpnQ

Will be interesting to watch this as you have almost the exact setup that I do (outside of gear ratio).

Wondering on driveline angle if using Bronco spring blocks would help, being the driveshaft angle is a bit steeper for the Bronco than the F-series?  Maybe a double cardan shaft?  I'll be watching this to see how it turns out.

I dont know how much help I will be but if you know just how much longer the GV is to the driveshaft hook up over what you have now it is easy but you CANNOT guess.

That is why it is best to get everything installed other than the shaft and do a measurement.
When you do the measurement the truck or car has to have weight on the suspension.
I then measure from where the Ujoint cap sits at both ends and let the shop, I have the shaft made, figure out then what to take off to put the measurement in the center of each cap.

Now do know if the trans or the GV uses a slip output yoke you push this in all the way and pull it out 1 inch then do your measurement. This will give you 1 inch of movement in and should still have enough splines engauged.

Also note if a shop is going to make a new one check with them on how to measure but the shop I used up north for many a drive shaft that is how they wanted you to do it.
I used the same way when I installed the Advance Adapter over drive unit, told them how I did it, down here in NC and it came out good.

I say document as much as you can as it is always good to have more than less information.
Did you get a new GV unit or used? If new why did you have to get install info from GV?
Dave ----

One thing you can do to minimize down-time is do what Dave is suggesting, but then while you are waiting for your new rear driveshaft lock your hubs, shift into 4 high and drive around in front wheel drive.

I don't know if the Gear Vendors has a slip yoke rather than a fixed yoke with a slip joint being needed in the driveshaft.  If it does this likely won't work.

But I drop the rear driveshaft in my early Bronco when I flat tow it, and I will often put quite a few miles on it, even at highway speeds, before bothering to put the shaft back in sometimes.

FuzzFace2 wrote

Did you get a new GV unit or used? If new why did you have to get install info from GV?
Dave ----

Thanks for the lessons learned, Dave.  I haven't received the GV unit (yes, it is new) with instructions yet.  I was hoping to be able to get my driveshaft ordered and perform a complete install inside a weekend to minimize downtime.

Nothing Special wrote

One thing you can do to minimize down-time is do what Dave is suggesting, but then while you are waiting for your new rear driveshaft lock your hubs, shift into 4 high and drive around in front wheel drive.

I don't know if the Gear Vendors has a slip yoke rather than a fixed yoke with a slip joint being needed in the driveshaft.  If it does this likely won't work.

But I drop the rear driveshaft in my early Bronco when I flat tow it, and I will often put quite a few miles on it, even at highway speeds, before bothering to put the shaft back in sometimes.

Good to know!  

I have called GV and discussed my concerns with the slip yoke on my NP208F (I thought "F" meant "fixed" but my yoke definitely slips out of the transfer case) and they assure me the unit they are sending will work with my truck.  I guess I'll just have to wait a couple more months...

New is good as no one has messed with it before you.

I know my drive shaft needed to be 7-1/2" shorter but sis not want to take the gamble it would be wrong once in.

Also part of my issue was I was changing transmissions going from a T18 to a NP435 even that they both measured the same I wanted to make sure.

One thing i did do is had a new drive shaft made for the OD and new trans.
This way if I ever want to remove the OD I can just slip the old drive shaft back in as the transmissions are the same face to tail.
In my case because the transmission shifter comes thru a pan bolted to the floor and I had the parts truck one I cut it and moved the hole back and kept the stock one if I want to go back with out OD.
Dave ----