My '57 310 originally came with an SM420 in it. When I got the truck, it was loooong gone. i plan to replace the SM420 now and am wondering if the "later" models are interchangeable. In other words, I found one out of a '66 and it is in decent shape. Will SM420's from that late of a model bolt up into my '57? Also looking for specs on drivelines. I have a stock 265, SM420 and stock rear....
Thanks-Dan
