[grandfisher]

I've been planning this project for a while now and I'd like to thank everyone for all the advice I've received and read in related posts. I want to cover all bases and avoid avoidable mistakes. I have a '76 Chevy, crew cab, 3/4 ton, 454, carb, 4:11 gears, and TH400. I need overdrive. From what I've gathered, my best options are a 4l80e, an NV4500, or a Gear Vendors unit. 4L80E is gonna be cost some bucks, with the computer control. Gear Vendor ain't much cheaper. I can get an NV4500 new for about 1700. I also have a 3:73 3/4 ton rear end I can swap to help also.
I would just like some different ideas or advice, pros and cons etc. Fabricating crossmembers, and installing clutch linkages and hydraulic clutches are nothing I can't handle. I need to cruise at 60-70. What would you guys suggest? Thanks.

 

[SSedan64]

Looks like you've covered most all options. You could get a 4L80E with a manual ValveBody, all up/down shifts will be manual tho'.

 

[grandfisher]

Yeah, I considered the manual valve body, but ultimately decided that if I'm going to have to manually shift, I'd probably be better off with a manual. A new 4l80e is around 2700 and I can get a nv4500 for 1700 and a gear vendor for 2700. I just want to cover all bases before I spend that much money and then find out there was a better option. Haven't completely ruled out the manual valve body but I'd still have to come up with a 4l80 and I'm trying to shy away from used ones. I think I've found a nv4500 with 30,000 miles for 700 bucks. Might have to give it a better look.

 

[Crosley]

I do not see many options with the weight of the vehicle you have to deal with and if a trailer is following your truck.

With the manual conversion , what would be the other costs invovled? Another 500 bucks or 750?

Some of this late model trans are not easily converted to a cable driven speed-O setup. It can be done , some times not inexpensive.

 

[grandfisher]

The speedometer problem can be solved for about 330 bucks with and electronic tachograph that receives the signal from the speed sensor and turns the speedometer cable at the appropriate rpms. I'm not real worried about the speedometer. It's something I'll probably put off until it starts to bug me. The TH400 is in perfect working order so I'm kind of tempted to go for an overdrive unit like the Gear Vendor but it's nearly $3000. I can get a new NV4500 for 1700 plus shipping. I might could put 1000 into the clutch components and the tachograph and come up with about as much as the overdrive unit. I'm sure the overdrive unit would be a faster install. I guess the overdrive unit wouldn't actually cost me as much more as I was originally figured.

 

[Crosley]

With the manual trans you may have slightly better fuel mileage with no slippage like a torque converter will.

Gear vendor is 22% over drive..

I would use a 4L80e , because I like automatic trans

 

[SSedan64]

Jakeshoe mentioned a Co. Auto Trans Incorporated in Edmonton, Alberta for the the 4L80E mechanical speedo housing $325 or http://www.shiftworks.com/tailhousing.htm#4l80E $500
http://www.transmissioncenter.net/speedometer_calibration_______va.htm#4l80e

 

[grandfisher]

I have nothing against a 4l80. I would rather have an automatic valve body than the manual valve body, so I have the issue of getting a computer controller. What would be the most economical or practical method for dealing with this? A computer out of a 4l80 equipped truck or an independent controller? I think the programmable computer controller runs about $750. I might be able to find a good used 4l80e for 750 putting the price to 1500. Plus the tail housing for a speedo 325 bucks. Somewhere around 2-2500 bucks should do the swap maybe? Thanks again for the help and advice guys.

 

[SSedan64]

If you were doing a Eng. & trans swap the OEM computer and harness from a donor truck would work. I don't think the OEM computer/harness is capable of running the trans alone.

 

[fast68]

if it were mine id go with a 700r4 from an 87-92 and use weld the 27 spline yoke to the driveshaft unless you can find a 27 spline driveshaft for a 2wd crewcab in a yard
although for towing the 700r4 isnt the best choice

you can find a better ratio axle for it and are somewhat common under these 3/4 and 1 ton single wheel trucks

theres a ratio in these 14 bolt 10.5 axle that was around 3.21 or taller i cant remember now exactly

 

[Torque454]

You don't need to spend $2700 on a 4L80E. You could buy a low mile junkyard trans and get a standalone computer and probably have the same cost or less than a NV4500 conversion.

 

[grandfisher]

You don't need to spend $2700 on a 4L80E. You could buy a low mile junkyard trans and get a standalone computer and probably have the same cost or less than a NV4500 conversion.

Alright. I think that this is starting to sound like the better option. I have a 700R4 that I could put in and a drive shaft that will work but I've been told with my setup, that I should shy away from the 700R4. I could probably get by with a moderately built 700 but I hate changin trannies so I don't wanna do it again anytime soon. I'm gonna keep a sharp lookout for a good 4l80. I've found a controller for about 750. Should I try to obtain a transmission from any specific year model? I know some 4l80 transmissions have different wiring harnesses both internal and external.
I'm not rich by any means but I have scrimped and saved enough to put pretty much whatever I want in this truck. I just don't want to spend any more than necessary or practical. What I mean is, I don't want to cut corners and throw something together that won't last or work properly. If I need more money, it will have to wait a little longer. So thanks again guys for helping me to head the right direction.

 

[Crosley]

A Trans from a junk yard is just that ... IMHO.

Get a 1996 or newer 4L80e if you go that route... look for the cooler line fittings.. one is at the normal case - bell housing area , the second fitting is near the back of the main case.

KEEP in mind the fitting at the rear case area is a special length fitting and that length design must be retained.

Wire harness and connector on the 4l80e was updated early and the same design remained for many years

 

[grandfisher]

Alright thanks. 4l80 it is. I think that I might start lookin for a core and have a fresh one built. I've got a good tranny shop not too far from me that has an excellent reputation. I'll give them a try.