I know, it's normally pretty easy to tell, however the truck I bought is Chevy chassis only, with a Ford body. So how can I tell if it's a first or secong generation 1955 based on frame/running gear?

After wire brushing the frame between the prior grinding and rust that was on it, I was able to read the following number " 55B 68 "

From what I learned reading some past posts the number that preceeded the 55 (which is now gone) would have told me if it was a first or second generation truck.

Are the frame measurements different between the series? If so, I was able to find the frame measurments for first, but not second series to compare.

The motor is a 1957-1959 (unknown which) with a 1954-1955 head on it, so that doesn't really help me.

Any suggestions or things to look at would be appreciated. I want to start ordering some parts, but a lot of things are divided by which series it is.

Thanks much for your help.