I've just been to the local parts store and had all three of these Delco alternators in front of me, side by side with the Motorola that came out of my 145. I know this discussion relates to converting the 122 from generator to alternator, but I thought I'd mention for any other 140 folks who happen upon the thread that the hole through the lower mounting boss on the 10SI is too small a diameter for the bolt used in my '74 145 (it threads directly into the block).