My '77 had the coolant recovery down low. When I did my fuel injection I wanted that space to put a small fuel sump with an electric pump in it. Plus the old style had the top open and when off roading the truck would bounce enough to come out the overfull spout on the top.
I moved the recovery tank to the wheel well like the mid to late 80's did. I bought one from LMC for a '85-'87 truck for $23.
But- the inner wheel well must have been changed sometime in those years. When I tried to mount it to my fender I found that it tilted quite a bit no matter where I tried to locate it on the wheel well. I "solved" this by stacking probably .75"-1" under one of the mounting holes.
Don't exactly have a picture of it... this kinda shows it.
EDIT: you might be ok. I looked at LMC truck about inner fenders and there was 2 designs. One from 73-80 and one from 81-87. So maybe you have the right "shape" fender for the overfull recovery tank.