overdrive

picked up this overdrive to use on the van, hopefully sometime this summer I'll get to it.
[i]

looks like you will end up having a very short driveshaft

From what I can see in the picture it looks like a divorced unit, which really makes a short drive shaft. IF it is a divorced unit, it will be even harder if not impossible to use it, as the front drive shaft will only be six to eight inches at the most!!! Meaning it uses a short drive shaft to the input side of your unit, and THEN the normal longer shaft to the rear axle. BOTH of these shafts will be way too short, especially the one on the input side of the unit.
I had a 4whl dodge that I was building, and used an over drive. The first time I TRIED the divorced unit, and no matter what I did, I could NOT get the vibration out of the front shaft. I finnally found a married unit and the vibration went away. Gear Vendors makes a very solid unit, and actually first came from Volvo, except Gear Vendors took Volvo's unit and made it stronger. They also have two types, one a divorced unit and also married units. The married units replacing the existing tail unit of the tranny and bolting on the overdrive. You are on the right track with an over drive like that, except for our wheel base just doesn't work with any of them.
The big advantage of an over drive after the transmission is that it actually doubles all the forward gears, so it makes a six speed out of a three speed. DEPENDING on the overdrive (or under-drive) per cent you can drop down from 3rd high, down into 3rd or even better 2nd overdrive and not over rev or over work the motor and keep the RPM exactly in the power curve. IF you can replace the tail stock on your transmission and incorporate this unit you MAY HAVE a chance with the drive shaft issues, if not, I have my doubts.
Old SKOOL

Found one on Ebay for $3,999!! It is known as a VERY STRONG unit and from the late 60's and into the 70's. Used in BIG horsepower units, with over drive per cents said to be from one at 30% and the other at 20%. From what I can see, YES they are a divorced unit like I suspected and do not see any possible way for you to use it/?? Even if you were to use a custom front shaft with the smallest yokes hooked together as a unit you could not get that part any smaller in length than maybe 6 to 8". And no way are you going to be able to not get any vibration there? let alone also the added length of the unit itself to now also leave you the rear shaft of about 8" or so I would guess?? Also, not sure but said to not be able to be shifted on the fly also.
Old Skool

Linoman you should check out DR driveline in hudsonville. they know their stuff and are easy to work with they will let you know if they can make it work.

The good old Hone overdrive!! yea baby- bullitt proof -these units have been run in everything including streamliners @ bonneville!! hard to beat these! There were /are? units made that even adapted to Gm & ford auto trannys rear tailshaft housibgs. Hone is still in buisness i do believe??

Here u go do a google= http://www.stangerssite.com/honeodrive.html

Man that is good info on the unit,, the married unit to the 9" rear axle sure would save some major room for the drive shaft,, will have to start looking for one of those,,, Thnx for the link,,,
Old Skool

Thanks for the input guys, looks like I stumbled on to a fairly sought after part in some parts of auto world. My unit is so clean I suspect it has never been installed on a vehicle, so if this just won't work on our short wheel base vans I'll put it up for sale,it should fund some of the work I need to do on the van.