hey all, here's my issue. i have two timing markers on my engine. i've been using the one on the right (see photo below) and its been working, but what then is the reason for the one tack welded to the timing cover? as the one on the right was where i expected it to be, I never noticed the other until i began my teardown to throw new heads and stuff on. am i supposed to be using the top one?

You need the one on the right. Someone used the wrong timing cover and added the bolt on one to get it in the correct position. That is, if you have the stock balancer, the ones for use with the 12 o clock marker is obviously different. it's rather easy to check the indicator groove on your balancer should be sort of in line with the keyway (a couple of degrees off) if it's there you use the bolt on tab.

thats odd. this is an acdelco reman block the previous owners had put in on an insurance claim. they for some reason put 193 heads on it, but it has a roller cam and an l98 block. no idea why or from where they got the timing cover... guess i just got lucky.

193 heads.... swirl port heads off a TBI engine? Probably the same place they got the timing chain cover. TBI engines used the 12:00 position timing tab welded to the front of the cover and they used roller cams. TPIs had it over at the 1:30 position like your bolt-on timing tab.

Makes me wonder if the whole engine isn't actually an LO5 350 TBI engine with the original TPI stuff bolted onto it. If that's the case, it won't matter since you're changine the heads and cam at this point anyway- and those were the two primary internal differences between TPI and TBI engines.