I have an Olds hydromatic and find almost no free space between the ujoint and rear end. I am used to sliding the drive shaft on to the trans spline
and sliding it back for a bolt up. Am considering shorting the drive shaft.
Any ideas?

 

Before doing the shortening, be sure that the engine/transmission has not moved rearward or that the rear axle has not moved forward due to some error. Also try to verify that someone has not substituted a part which would lead to the condition. The "open" driveshaft vehicles usually have sufficient movement so the driveshaft doesn't push on the transmission. I have a '55 with a Hydramatic and there is sufficient "slide" on the transmission's output shaft. I don't have the shop manual for the '41 so I'm a bit unsure if it is different.