That's factory. The piece tying the mounts together is the bracket that holds the fuel lines when running dual tank option.https://www.ebay.com/itm/Rear-Cab-M...-/224262280658?_trksid=p2349624.m46890.l49292
Then I found this.
Not sure if that wimpy "crossmember " is factory but what the hell? Lol
The two piece rear cab mounts and one piece make no difference in 2 or 4wd. I've seen both types used on both.
I will have an answer in a few hoursBefore you go cutting that out, does @imiceman44 have anything?
The different height on the rearmost cab mount only applies on 73-80 trucks only.
NoDon't you have a spare frame underneath a yellow cab laying around beags?
Didn't say I got rid of it.Got rid of it already? Lol.
I thought you hadn't really touched it yet. Now that I think about it you did say the fenders were off![]()

So this is a picture from the bottom of my 89 crew cab k30, seems like the one posted by Kenny as a 2wd.To answer the question, I didn't want to hack that frame up any more then I needed to. I currently have a plan for it.![]()