Jeep J20 6.5 swap tranny/TC question

[jteckmann]

Hi all -

First, wanted to say this is a great forum, and I plan to be a long time lurker while I'm in the planning stages of my swap!

I have a '78 Jeep J20, TH400 Tranny (AMC bellhousing), and the full-time Quadra-Trac (BW 1339)

I'm preparing for a 6.5 swap and am still searching for the elusive "perfect donor"

My question is more Jeep specific, but hopefully someone can point me in the right direction:
Will a 4L80 work with my Qudra-Trac? I've been searching on AA and Novak, but looks like I'm outta luck.

I'd like to have an OD tranny when I finish this project. My understanding is that I can get the Qudra-Trac to work with a 700R4. But I want this truck to be a capable tow rig when I'm done .... will a well-built 700R4 hold up behind a 6.5 that's regularly towing up to 8,000lbs?

Or do I just have to choose between the keeping the Quadra-Trac or gaining Overdrive? (i.e. look for a NP 241/4L80 combo donor?)

[More Power]

If it comes down to it, I'd opt for the 4L80-E/NP241. To my way of thinking, a durable OD auto would be more important than maintaining the QT.

I swapped out the TH400 in a 1989 GMC 2500 a few years ago for a 4L80-E. Aside from needing a new trans/transfer case adapter, it was a bolt in. Input/output splines and bolt patterns all matched. Unless you discover differently, I'd not assume a 4L80-E won't also bolt together with the QT.

Jim

[JeepSJ]

MP - One reason for wanting to keep the QT tcase is that it has an offset output for the rear, and the rear diff is offset to compensate. Changing to a 241 would require a new rear end with a centered diff. 241 also has the wrong side output for the front.

jteckmann - A good reason to scrap the QT is that everything is driven through the chain all the time, which makes it not the best choice for towing. Chain stretch is a problem. Converting to a 4l80e/241 would add some definite strength, and GM 14-bolt housings are fairly inexpensive.

My advice - go sell the QT over on ifsja.org and find a 4l80e with a transfer case that has the correct front output (like a 208) and swap in a centered D60 or 14bolt rear.

[jteckmann]

Thanks or the info guys!

That's sorta what I figured - that OD trumps the QT, and keeping the QT/offset diff would cause some headaches.

So I'll be keeping my eye's peeled for a 4x4 4L80 donor that I can get the whole rear end off of as well.

[HH]

If you are set on using the offset rear, you could also use an older Jeep Dana 18 TC with the offset rear output. Adapters are available at Novak (http://www.novak-adapt.com/) and Advanced (http://www.advanceadapters.com/). But IMHO you would be better off with the 241 & GM 14 bolt or Dana 60

[uglyjeep]

I know this is an older thread, but...

Another option if you want to keep the rear offset diff is a dana 20. Yes, yes, I know that they normally have a centered rear output, but the parts off of a dana 18 will bolt on. I know this because one of the POs installed one under my 75 Cherokee. But you still would need the adapter to bolt it to the trans I guess.