well I just got off the phone with Ames Performance, I was going to order an indash Tach ( 1969 GTO ) and I was talking to their Tech Dep about compatability with my MSD 6200 box and MSD Distributor and he said he could sell me a Tach and a MSD Adapter but it would never give an acurate reading they are more for cosmetic looks and are not a quality tach and that they have a lot of problems with matching them to MSD.He said it was a better bet to buy a quality tach and stay away from the repro stuff as it is low quality stuff. Nice guy to give me a heads up before I spend my hard earned cash.