Dave, if it has the higher gear set, you will probably need to order a gear that is thicker than the lower gear sets. The actual width is different. This will take up the space difference. Not uncommon, and readily available. Where are you at in Washington? If you're near the Seattle area, call Randy's Ring and Pinion. He'll have all the knowledge, and parts you'll need at a good price. My buddy had him redo an 87 Vette rearend that is going in a 62 Vette. I'm sure some of the other guys on the site can give you exact numbers and specs.