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So I have a line on a 6V-71/auto transmission in an early MCI MC-5, I think an A.  It has an Allison 644 type transmission, not sure of the exact model because we can't see the tag yet.  The question is - if I get this, will I have the right parts to then install the transmission on my 8V-71?  I am presuming the rear housing, the flywheel/flexplate crank adaptor, etc would have to be swapped from the 6V-71 onto the 8V-71.  It's remotely possible that the transmission is actually a 740 (it looks like a 640 type, but what  do I know, I've never actually seen either in the flesh).  In that case the question is, would I have the stuff needed to transplant the 740 plus either the 6V71 turbocharged (yet another story I know) or the more obvious add a 6V-92 to the 740.  In that case I would have the motor mounts and cradle for the 6v-92, plus the adaptor that would put all the accessories in the right spot (air compressor, alternator drive pulley, power steering pump) for the bus if the engine came out of a truck or something.  Would the flexplate, crank adaptor that came off of a 6V-71 fit on either a 8V-71 crank or a 6V-92 crank?

My bus is a 1980 MCI MC-5C.  I'm trying to figure out what options open up if I bring this drivetrain home...

thanks. Brian

From my messing around with this, the 71 series stuff is different from the 92 series.
The stuff includes the crank adapter & bellhousing.

The 740 is longer than the 644 & will leave you with a shorter driveshaft. In their MCI 5's, Custom Coach used 8V71 & a HT740. very short drive shaft indeed, but a friend has one in TN & he knows the difference between a 6V71 & an 8V71 & what a HT740 is.  ;)

So, I think the flex plate & adapters will work on your 8V71, but you'll have to shorten the driveshaft to a length you won't be comfortable with - at first . . . Worst thing would be accelerated U-joint wear. While there is a possibility of trans output & dropbox input bearing wear, I'd doubt you'd notice over the miles you place on your coach. . . .

One other thing:
I'm still collecting parts & haven't installed this yet.  ::)

I had a VS2-8 in my 4106 and the driveshaft was 17 inches, keep it greased and no problems in ten years.>>>Dan