TH400 swap to 4L60E or 4L80E

[Peewee]

Truck: 1989 C2500 5.7 TH400 trans with 4.10 rear end
Sitrep: Will need to tow a 20' car hauler all over the midwest this coming summer - about 5500 to 6000 lbs max never more.
Question: What would you do? A) leave it alone be happy with 60 mph and 9 mpg. B) Leave TH400 in it and swap out to 3.73 rear end. C) leave 4.10 in and replace TH400 with 60E or 80E. D) spend 12K and get a different new to me truck with 150K miles on it.

The truck is in perfect condition with 120K miles on it so don't really want another truck... I have 2500$ to spend maybe a little more if needed...

any thoughts?

 

[94burbk1500]

TH400 to 4L60E would be a downgrade. If memory serves me correctly, the 4L80E is based off of the TH400 but with overdrive and I think more clutch packs. If you can find a steal on a 4L80E and computer, go for it, otherwise i'd stick with the TH400. You could also look into Gear Vendors to add overdrive to your TH400 and not have to worry about a computer for the trans.

 

[454cid]

I would swap rears, if anything. Maybe make a trip or two as is, and then decide if taller gears would work for you.

I'm under the impression that swapping in an electronic controlled transmission, even with a fancy controller, still require fiddling to get it to shift the way you would expect it. I've never looked into it deeply, only reading other's projects.

 

[Peewee]

I do like the idea of just doing a rear end swap. I don't think I have the power to go all the way down to a 3.42 but a 3.73 should drop me a few hundred RPM at 68 to 70 mph. After spending a few hours looking for and reading about the 4L60E's and 80E's it seems one would have to go with a 80E as the prices are about the same. All reports seem to indicate that the TCI 302820 EZ-TCU controller that I would need is a solid product but 600$ and a significant amount of work to dial it in. Anyone use one of these?