Quick Question about Detriot 671 & 6v71

[Brandon314159]

Hey all,

I am Typ4's son Brandon.

I have a quick question regarding Detriot engines.

My 1955 GMC coach has a 6-71 in it matched up to an Allison VH transmission (single speed, converter lockup or unlocked).

I am interested in swapping in a newer transmission but they all come off of 6v71 engines (Like the Allison V731 series 3-speed auto).

Anyone have an experience with these? Is the swap possible? There are also VH-3 and VH-5 transmissions out there, but even those are starting to become 35+ years old and thus a little hard to get hands on.

Any help would be appreciated.

If I had my hands on a different powerplant that would fit, I would swap it all over to CAT or Cummins power for some real getup-and-go. For now the Detroit does a good job of turning diesel into noise.

I will do a posting soon of the project

P.S. I am also looking for a 6-71 head w/ Jacob Brake (Jake Brake)

Later,

-Brandon
'55 GMC TDH-4512 Coach
'82 Mercedes 300SD Turbo Diesel
'65 Unimog 404.1 Radiobox
'74 VW Rivera
'69 VW Beetle
'79 Suzuki GS550

 

[typ4]

I would recommend you call Gary at 1-800- allison. Tell him who you are and that I said hi.

 

[FordGuy100]

$5500 Will buy you a 1997 8.3 cummins (325hp) and MD3060 tranny with only 80K on them. Out of my parents totaled RV.

 

[The Warden]

Hey Brandon!

I don't have much experience with Detroits in on-road applications, but my guess is that the 6-71 and the 6V-71 used the same bellhousing.

Also, you might do some research on Crown coaches...they were pretty much all school buses (although I think there were a few transit variants out there), but almost all of them from the '60's on had 6L-71's (basically an inline 6-71 "pancaked" on its side). I think the majority of them had 5 speed manual transmissions, but IIRC there was an Allison automatic available as an option in later years. You might find out which tranny was used, and see how it compares to the single-speed that you're dealing with/

Hope this helps a bit...good luck! Sounds like a fun project take pictures!!