Swapping in a 4 speed manual into my 89 K5
 

I tried searching around for my answers and haven't found what information I was looking for. I am getting ready to swap in a 4 speed into my 89 K5... it's not the SM465<for now> I have pretty much everything I need sans a few little items.... My question is am I gonna need any sort of adapter to mate to my NP241? I just want to make sure I get everything I need to do it right and not drag out not driving my Blazer any longer than I have to.... Like I said I had been searching around for info I just don't know if I was looking in the right places, so even a helpful point into the right direction would be great! Thanks!

It all depends on what you are putting in and what you are taking out. You must match the output shaft spline count & length with the replacement transmission to get it to mate up properly. Typically manual transmission vehicles have a lower spline count output shaft.

Your truck would have come equiped with a TH700R4 transmission which should have 30 splines on the output shaft.