yes on the older blocks they have the 2 sizes, pre 197?. on later ones all 4 bearings are same od. the id is same on all bearings. i hope your machine shop would know this already. they are not too difficult to install yourself and you would know they are right and wouldn't cause binding on cam. you just have to be careful to get the oil holes lined up perfectly and you need a can bearing instailation tool. mine has already paid for itself with the 250 and 292's i've done.