Im new here and this is my first major project I inherited a 49 chevy 3100 and my first problem im running into. Im putting 3:55 gears in the torque tube and the kit i bought has a okie bushing and i removed the 2 bushing and seal. The new bushing is not long enough to reach both holes. Do i put the old rear bushing and pin it. Or tap the other hole and seal it. Need help.

The Oakie busing is designed to be installed while leaving the rear bushing in place. It is this way so the Oakie can be installed with out removing the drive shaft,etc.
I would reinstall the original rear bushing. With this set up the Oakie will be riding on a fresh unworn part of the drive shaft....which is good.

Gene, if someone had a brand new rear bushing on hand, would it be worthwhile replacing the original rear bushing before installing the Oakie?

Thats what i thought but wanted to ask to be sure and should i put a new bushing in first?

I would suggest that you measure the ID of the tube and the various ODs of the Oakie assembly. I have read of a number of folks that tried to install one only to have it jam part way. I installed one in my 38 Master and the force I had to use was considerable.