Hey guys. ive got a question about transmissions, specifically, overdrive units. What would be better?

T-19 W/ Gear Vendors .VS. ZF-5?

I obviously know a ZF-5 W/ Gear Vendors beats a T-19 W/ Gear Vendors, but it would involve swapping in if I got a Pre 87' IDI. And now yur askin "why are you putting a Overdrive unit on an Overdrive transmission?" The answer is because I want something that would give a good final ratio when im runnin empty down the hwy, It also turns the 5spd into a 9spd. I could drive just the regular 5spd's when im empty and use double over on the hwy, and I could use all the other Overdrives when im towing.

 

And im not intrested in Brownie Boxes.

 

Sounds like you want the ZF / Aux. Thats what im planning. That way i can keep the 4.10s and still cruise down the road at a decent RPM

 

I've got a ZF-42 and a GV; with 4.10s, I'm running about 1600RPM @ 60MPH. Makes for nice low-RPM cruising, but on (long)steep hills I have to downshift. I've even towed a trailer with this setup, in double-overdrive. works decently, but the low revs and lack of overall power do hurt my hill climbing ability.
GV works nicely, and I've got it setup with a switch on my gearshift, usually don't use it until after I get into 5th with the ZF.
Edit:
That being said, though, one of the things I did while tuning up my truck was put high-grade, expensive Royal Purple manual transmission fluid(lightweight stuff) in my GV and ZF; so far, nothing seems to have melted/overheated/started to smoke, so I think it helped. Note that the reason I did it was because I didn't want to /ever/ change the fluid - I expect the fluid to outlast the (zf)transmission, and I'll probably rebuild/replace both when something fails.

 

zf5 + gear vendors w/ 4.88 gears.
have it all.

 

Only reason I ask is because the truck comes with a T-19. And well, Gear Vendors really isn't cheap. Neither is a used ZF-5. Plus, not too sure on the ZF-5 swap details

 

ZF-5 can be done with essentially stock components. A GV requires you to do custom install. If your T-19 trans is good shape, the question is a bit less clear. If T-19 is worn out, then a good ZF-5 will be cheaper cost and fairly straight forward installation using mostly factory parts as stated previously.

Assuming your T-19 is good shape, that is a very strong trans and a GV would give you ability to split the 2/3/4 gears if needed. ZF-5 no possibility for that.

While the double OD potential is nice, your costs are also much higher than a T-19/GV or ZF-5, since you are going from T-19 alone.