[MX145]

Not sure if this helps but I had similar issues with my 68 subframe when I went to align the car. I'm running DSE parts but ran into the same situation. The factory tolerances apparently have a wide range. (Beyond 1/8", at least on a Friday). DSE uses a jig that mounts to the motor mount locations and the UCA mounts bolt to it to positively locate them for welding in place. The jig didn't want to sit in the car properly. It was raised up off the crossmember. I had to shim up the jig with multiple shims and slot the motor mount holes just to get the jig mounted. I made sure to keep the jig level and used the same number of shims and hole offset on both sides. DSE told me they haven't run into this before. I noticed the car was heavily shimmed on one side when I bought it but thought something in the ams on that side was bent from a previous owner accident. The frame itself measured out to the GM specs and measured square. Turns out my UCA mounts were off a 1/16 on one side and 3/16 on the other totaling a 1/4" difference between the two. The factory UCA locations were off as well as the crossmember itself wasn't centered. I couldn't get negative camber on one side and the other was in range. The 3/16 on the bad side had a huge impact on the static camber. I thought about machining down the UCA shaft as well but I didn't want to modify a good part to make up for another one out of spec. I would have had to take way too much off anyway so I bit the bullet and cut the UCA mount out and moved it to match the other side. I had to move it approx 3/16. I tacked and measured and checked hub angle what seemed like 20 times making sure my UCA mount height stayed in place and the camber matched with the same number of shims as the good side. This probably goes without saying but the mount can pull on you from the heat tipping it in or out so I went back and forth on my root pass to get it stable constantly checking before the final weld. Maybe both of our sub frames came from the same guy on the assembly line. He must not have built too many of them.