So, your truck still has the original torque-tube drive shaft/ rear axle? Did you have much trouble removing the trans? If it is still the original then only another torque-tube trans will fit in its place.
I don't know your experience level, so don't be insulted. Do you have a shop manual? There are lots of resources online:
http://chevy.oldcarmanualproject.com/The shop manual is here
http://chevy.oldcarmanualproject.com/shop/1948_51truck/index.htmGood luck.
Oh, post some pictures of your truck. We all love pictures of old Chevy trucks.
