"Where does the original tab bolt on on a 350 block and what's the best source for the OE M tab ?"
Pete,
It's attached by the screws that hold the timing cover to the front of the block. If you PM me your email address I'll send you a photo of the one on the 350 in my '32 Ford roadster street rod. A lot of street rod builders are into bling and throw away the OEM tabs. I'm sure you can find one for the cost of postage. If I had an extra one I'd send it to you. It's not as though they wear out.
If you get on the Chevy Talk forum it's pretty likely someone would have one for you.
