Yes they do, in fact you can find a lot of 78 - 79 Wagoneer's with 360's and TH400.

Even if you have the 401 fly wheel you can have it re-balanced.

The retro fit to adapt the TH400 should not cost more than $50.00 (output shaft, housing, and slip yoke) from the tranny guy... but you will need to add it to the total cost of the rebuild.

A second gotcha is the drive shaft. With any transmission swap you must have the proper length drive shaft.

You have my order wrong.

1) Rear end ($100.00)... since the 90's 68 and 69 B-bodys are hard to come by; but it is worth the effort if you want a quick and easy setup. Note you will need to grab the shock plates and it is best to get new replacment U-bolts. PS don't trash your brake lines... they will fit on the MOPAR axle just fine if you don't mind a little work. AMC had done right with aluminum brake lines... old steel lines are a bit rusty now these days.

Another thing 71-73 Mustang rears are close but need the purches moved 1/2"... a lot of AMCrs have been able to bolt them in (Mostly because of old rubber in the spring eye bushing), but will make the springs point inward.

2) TH400 ($100.00 core) $600.00 on up on a good rebuild plus additional costs for Tranny mount and the drive shaft length adjustment.

3) Gear Vendors overdrive over ($1950.00 installed) + cost for drive shaft length adjustment.