[gringoloco]

Moving to the rear, we see that GM located the trailing arm crossmember 70.43” from the core support CL. This is derived by adding the seemingly arbitrary 38.40” reference from the core support bushing CL to the 32.03” measurement, which appears to align with the forward-most upper crossmember mounting hole. Correctly ocating the trailing arm crossmember also correctly located the rear axle CL.

This measurement seems to fairly accurately correlate with findings here on the board of previous conversions (including my own), which utilize existing holes in the 4wd frame, following removal of the existing bracket (photo courtesy member notsolo). This reference gets us in the neighborhood. We will see how it pans-out with the location of the DEG c-notch, which due to the contours of the frame, is relatively fixed.