Just got done with welding the bottom of the core support back together, tried last night to re-install but the hole on the drivers side is off by around 1 1/2 inches. It's too far towards the back of the truck. I was SURE I got everything right when i welded new mounting holes and supports into it. I have the fenders installed now and the drivers side is definitely off, but only by about 3/4 inch with the fenders on. Also, the truck is not on level ground, does it have to be on level ground? And the cab is shifted about 1/2 inch down hill. Would this throw off the core support alignment?

 

I would start by getting the truck level, at least from side to side. Front to back isn't as much of an issue, but you want to be sure the frame isn't twisting any.

 

The front frame rails can twist a little without the radiator support or bumper installed but I can't imagine enough to prohibit installing a rad support. Let me know if you need measurements. Checking a rotted out rad support and ballparking the hole center on the rotted side gives 44" c/c on the mounting holes.

 

I made some good progress today, the rad support is in and fenders are back on. I think the problem was that, in addition to not being on level ground (I've since moved it to a close to perfect level spot) the bushing hole on the drivers side was about an inch too far forward. This is because I welded the bottoms of the support back together from a rusted out state. It was difficult getting good measurements. I had to hack out about a half inch of the hole, and with getting the truck on level ground it lines up pretty closely. I'll have to message you if I need some more measurements, I never thought to ask someone on here. I actually looked up some core supports on eBay and scaled the hole locations from a known measurement on my support (the little u-nut that is on the bottom where the splash guard bolts to) I had my calipers up to my computer screen measuring the picture on eBay. not the best way but it gave me an idea, which I needed because there was literally nothing left of several spots on the lower part of the support. Getting the cab lined up wasn't too bad. I had to move it 3/4 of an inch. I put a cargo strap around the frame and into the hole on the front of the rocker panel and tightened it. Then I took a spud bar with a 2x4 against the opposite side rocker panel and just bumped it back and forth a bunch of times. It moved far enough so it was pretty close to perfectly in line.