Squealing kind of noise

[85chevy86]

I put a new 350 in me truck last month and finally got to drive it around. Well I drove it on two short trips and all was good. When I went to drive it the third time I was getting a loud squealing type noise but only under accelerating. I checked the headers and the driver side one was lose I tighten it up but it still makes the noise but I don’t think it is as loud now. I got new gaskets on the way to work thinking I may have blown that one out. Is there anything else I should check if that is not it?

I also read that it could be the speedo cable. I did not think about looking at that when I was driving but I do know it use to bounce a little around 20-30 mph.

The 350 has a bigger cam, roller rockers, and Pete Jackson gears. Its in a 1986c-10

Thanks
Evan