Another part that should be mentioned is the 2nd and 3rd gear clutch. I find most of them to be worn out most of the time. Somewhere in 53 or so they changed from a GM p/n 3705112 to a p/n 3713535. The difference is easily identified because the older style has two dogs and the later one has 4 dogs. The only source for this part that I have found is eBay. Used ones are usually not worth installing. The transmission has to be disassembled to install this part.