4104 GMC Auto Tranny

[draker]

I have a 1959 GMC Highway Coach with a 4 speed standard tranny and I want to change it to an automatic but I don't know want tranny I can use and what years.Can anyone help me out.

[draker]

The bus has a 671 Detroit with a V drive standard in it.

[roadrunnertex]

For what it would cost to install a V730 transmission and change the rear end out the 4104 rear end won't work but you will have problems with driveshaft vibrations as the angle is wrong.You have to go to a rear end out of a PD4106.
With the 6/71 and it's V730 the old bus becomes a very slow bus out on the road.
As much as I love the old PD4104's it is not a good idea to do this project.
I would suggest going with a later model MCI with a automatic transmission and a 6V/92 or 8V/71 then it's a factory installed every thing will work just as advertised.
A ball park figure just for parts V-730 used running take out $1500.00
PD-4106 rear end $1500.00 + or -.
Misc.Parts to make this project work $1000.00.
ball park figure $4000.00 +or-
Now we have not even figured labor at $65.00 per hour.
For what it's worth.jlv

[Dallas]

JLV,
Why not a VS2-8?

That would be pretty bullet proof behind a 6-71.
The angle would be right and it is rated at 259HP. It also is an OD.

It's also possible to make it a selectable transmission with some judicious plumbing and wiring.

Just a thought. I've never been really fond of the V-700 series as they are too complicated and use too much hp just to get moving.
The VS series were more robust and could be rebuilt on the side of the road if it was needed with only normal mechanics tools.

Yes the V-700's are newer, but is that really neccesary for a bus that's almost 50 years old?

[roadrunnertex]

Dallas,
I don't know that much about the VS2-8 transmissions.
But it's still going to cost money to do the change over.
And you have a 6/71 in the bus with a VS2-8 is it going to be a performer going down the road?
Any thing is possible with enough time and money!
jlv

[TomC]

The easiest conversion (in my opinion) would be to get the entire drive train from a transit that consists of the 6V-92TA and V730.  You'll have nearly twice the power with a modern power plant.  Good luck, TomC