Hi,
If you will check, you should find that plane/angle of the center line of the engines crank shaft is at the same plane/angle as the pinion shaft of the rear axle, with regards to the line/plane of the frame.
It is most important that the plane/angle of the aux. trans be the same as the engine and rear axle. U-joints will last longer.
The length of the drive shaft should be long enough so it can be easily install and removed. The angle is not that important, it is that you maintain the same plane as the engine and trans.
I spent many years working for Standard Auto Body in L.A. installing aux. gear boxes, PTOs and Hydraulic systems for utility company vehicles. I also, worked for Jumbo Equipment Co. doing the same type of work.
If you have enough length, do as PaulyBuilt, Use the rear U-joint on aux trans in place of the Drive Shaft carrier bearing (Center Support Bearing).
Good Luck, hope this is of some help.
GMCPic
