Just curious about something here. I have a 96 Chevy C3500 crewcab dually. I would like to add another gear for highway driving and wondering if anyone has heard of a upgrade kit that will allow me to replace the 4L80E with one of the newer Allisons? I love my existing truck and would hate to trade it just for the trans. Also I am not too keen about the 45K price tag on the new trucks. Does anyone have any ideas?

Thanks for the help guys!

I'm not trying to deter you from doing this, but I can say from experience (my 80 K20 started with a TH350/NP205 and swapped that out for a 700R4/NP205 and am now in the process of converting to 4L80/NP205.

You have to consider the purchase price of the Allison $$$, mating ability to your current transfer case (others are probably better to answer that as you may need a new case or you might get lucky with just having to buy a new adapter and/or input shaft), then there is the electronics to hook it up $$$, then drivetrain mods, firewall/floorpan clearance (body lift???), and quite possibly exhaust modifications.

Again, not saying don't do it (as I did it twice to one vehicle), but the cost (although cheaper than a new rig) might not be worth it.

It would be nice to hear what exactly is involved though (I know I'm curious).

If you do decide to do it, Good Luck :ro) and keep us posted.

Just curious about something here. I have a 96 Chevy C3500 crewcab dually. I would like to add another gear for highway driving and wondering if anyone has heard of a upgrade kit that will allow me to replace the 4L80E with one of the newer Allisons? I love my existing truck and would hate to trade it just for the trans. Also I am not too keen about the 45K price tag on the new trucks. Does anyone have any ideas?

Thanks for the help guys!

I have seen a great product for you , look up Gear vendor or Ranger gear splitter. These two unit give a extra high over drive ratio. Good luck

I have seen a great product for you , look up Gear vendor or Ranger gear splitter. These two unit give a extra high over drive ratio. Good luck

http://www.gearvendors.com/

Gear Vendor is what I have been looking at prior to thinking about the Allison. I figure for the money it costs for gear vendor ($2500) I shouldn't be too far out of reach for swapping the whole tranny to an Allison. Any ideas which is better? I build street rods with late model fuel injection engines so the wiring doesn't scare me. Just wondering is anyone has done it and what problems they have come up with. Also curious if it is the same bolt pattern on the bell housing. I am running a 2WD so I don't have the transfer case to worry about, although I don't know about floor pan. This may all be wishful thinking but would really like to hear your ideas.
Thanks

Jperry,

The current Allison's extra gear is akin to a manual's granny gear. For driving highway speeds that obviously won't help much.

The Allison for 2006 sports 6 gears, the 6th being a double-overdrive. Plain to see it will be harder to get your hands on at first, but maybe you should wait and see if you can grab one of these newer units.

Sounds like a good idea to me, do you have any idea what bolt pattern is on it?

I haven't seen any hard information about the '06 bolt pattern, but GM has always maintained bolt patterns... I'd anticipate an easy hookup.

Ford owners have never been so lucky.

Sounds like a great idea, however I don't think you could clear the allison w/o a body lift becaue of its huge size. Without modifying your floor pans or using a body lift I don't think you will be able to clear it. ANYTHING can be fabbed together with enough know-how and/or money.

Body lift is preaty easy to do I would suspect it would look like the older 3500 HD. Now if we can get someone to tell up whats involved with electronics .....hint hint

I'd go for the Gear Vendor unit. That way you have the best of both worlds, high and low gears, gear splitting, and it is truely a bolt in deal.....well, with the exception of a new driveshaft. But very slick unit. I know a guy that had one in his 1ton 98 6.5 with 4:10 gears and at 120kph it would rev just under 1800rpm! NICE!

The only bad thing I have found with gear vendors is the price. If memory serves me correctly it was around 2700.00 bucks. Even if you found an used one people still want around 2000.00 for them. It just seems for that kind of money an Allison wouldn't be all that much more if we could figure out the electronics of it.

The only bad thing I have found with gear vendors is the price. If memory serves me correctly it was around 2700.00 bucks. Even if you found an used one people still want around 2000.00 for them. It just seems for that kind of money an Allison wouldn't be all that much more if we could figure out the electronics of it.

Jperry,
Another vote for the Gear Vendor (GV) unit. You're gonna pay over 2700 bucks for a used Allison....right? I mean, I think just the upgrade from the 4l85E to the Allison is like $2400 in a new truck. Unless you have a source for really cheap trannys you're gonna be way over 3 grand (GV+install) to buy an Allison not to mention...as posted by others... the electronics, bodylift and installing it in your rig. In addition, you wouldn't really be gaining anything from the Allison the OD is about the same and the other gears are just a tad closer together. With the GV you will split each gear (for a total of 8 speeds) giving alot more flexibility. If GM starts offering a "crate motor" style kit for the new 6 speed I might think about that, but I doubt it'll be a cost effective upgrade. However, it will have major Gee Whiz points and that is definitely worth spendin' some cash. My $.02.
JP

I would find somebody else who had a gear vender in your application and see if they like it in there's first. I put one in my 95 K2500 suburban and had nothing but nightmare vibrations, no solution to the problem and now I am left with other vibrations caused by the gear vendor. I'm not saying it won't work for you, I just know first hand that it was a nightmare in my application that could not be rectified.