Is it "practical" to disconnect bolts, lines, and linkages holding trans, transfer case, etc., in place, slide entire assembly rearward, and replace seal? TIA

 

In theory yes

I had to change one out a while back

You preferably have a good trans jack arrangement to raise and lower the assembly to the ground, the TC case makes balancing tricky, several trolley jacks will work at a pinch

I use a slide hammer with self tapper to remove seals, I first drill a very small hole in the seal case, tape your drill, never failed

I find having either long studs or bolts greatly eases installing the trans to bell

before installing make sure torque convertor is carefully and fully seated

I recommend establish and measure correct TC depth in case upon removing trans

You wont save all that much time on sliding it out from under the truck

take adequate safety precautions

I found the cooler lines are retained within the AW4 with plastic 3/8" fuel injector connects.

After 25 years, these were brittle as burnt toast, thats how come I know what size they are

The whole cooler line system was cactus, I had to replace it with custom parts