Jason, I just finished putting a 4 speed saginaw with Patricks custom shfter in my 53 gmc this weekend. I already had a open driveline. I can't even begin to tell you how much better it drives. After I drove it the first time I couldn't keep the smile off my face. I just love it. I also have a 3.08 gear. The saginaw is a very easy replacement. Direct bolt in. Only had to add longer bolts with nuts and lock washers to the bottom transmission bolt holes. The saginaw was only 1/4" shorter so I didn't have to change driveshaft. I have about $500.00 in my trans and shifter. And the trans was rebuilt. Well here's at least one other option.
