79 F150 4x4 parts rig

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Feb 28, 2020 | 02:03 PM

carnuck

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From: Seattle

79 F150 4x4 parts rig

I found this parts truck less the axles (351W/C6/NP205? 208? Wrecked by PO) and was wondering if I can use the tcase on my ‘88 F250’s C6 (from 460 2wd) with minimal digging into the trans to convert it to row trailer. I wish I had an O/D auto for highway speeds.

Mar 5, 2020 | 11:51 AM

Nothing Special

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From: Roseville, MN

Putting a transfer case on a 2WD transmission requires completely disassembling the trans, replacing the tailshaft and the tailshaft housing. Definitely not in the "minimal digging into the transe" territory.

The exception is a divorce-mount transfer case. Those use a short driveshaft between the trans output and the transfer case input, so they will have a U-joint yoke on the input shaft. (I know at least some Ford trucks in the early '70s used divorce mount transfer cases, but I think by '79 they were all "married" versions.) But mounting a divorce mount transfer case is a little more involved than just bolting it to the rear of the trans. You need a stout mount for it.

And how would adding a transfer case to a C6 address your desire for an automatic overdrive?

Mar 5, 2020 | 01:40 PM

carnuck

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Quote:

Originally Posted by Nothing Special

I could run taller tires with my current tall gears and low range would give me the takeoff power for towing. Not an O/D but it has fairly tall gears that can do 70 with the right tire size. I went down to 30” as a compromise for take off power but 33” would still fit and maybe bigger to do 70 on the highway with less RPMs and save a bit more wear and tear and a bit of fuel. I think it has 3.08 gears but I forget and the truck is getting an oil and filter change right now so I can’t check. It’s about to roll over 90,000 miles and it used to haul 5th wheel before I got it.
I wish I had time before the Moonshiners swap meet to load and go to it since I’m in Tacoma this year.

I had hoped the C6 was the one I pulled the rear shaft out of after undoing the tail stock and swapping the 4x4 one in but maybe it was a C4 or early Borg Warner. I only had to install new snap rings like on an old school Honda CV axle inboard end. The bearing of the output tailstock kept it from sliding too far back but there was an O/D that would fit there. No low range or tcase as they didn’t make them yet during the Rambler years (pre ‘71)

Mar 5, 2020 | 03:53 PM

Nothing Special

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Quote:

Originally Posted by carnuck

I could run taller tires with my current tall gears and low range would give me the takeoff power for towing....

I've heard of people using low range in a transfer case to get rolling and then shifting into high while moving. Neither Ford nor I recommend it. Transfer cases really aren't designed to be shifted between ranges while moving. If you can match speeds well enough it can be done, but most transfer cases I've used have been pretty balky, so it's hard to know exactly when it's going to shift. That makes it even harder to match speeds.

Mar 5, 2020 | 03:58 PM

carnuck

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Quote:

Originally Posted by Nothing Special

I had a High mileage Jeep stroker Mexican 6 with 999 auto and NP208AM in my ‘83 Cherokee full size with 2.72 gears 31” tires and I got quite practiced at it. Downshifting was tougher. Especially on 10% hills while hauling the trailer I made out of a bus when the stupid lockup converter engaged at too low of speed.