Flywheel cover doesn't fit

[master 1969 c10]

I I have a Chevy Turbo 400 modulator is in the back of transmission and transmission pan is the shape of 400 pan. I bought aluminum one about 5 years ago and the holes don't line up the holes the holes close to the transmission is 10 inches Center to Center and I took the cover to jegs and the one the had came up the same measurement of the one I have so it doesn't fit either and there is no spacer adapter on the transmission the bellhousing is a direct bolt-on to the motor has anybody else ran into this problem did one or two years of the Turbo 400 have a larger flywheel pan bolt pattern. My truck is coming along but it seems like I take one step forward two steps back. The top holes are about 1/2 inches off needs to be longer. Thanks Doug