i have a '78 Chevy 4x4 with the "eye" type latch for the hood. when i got it the release cable was broken in two so it was replaced with a LMC repro. when going down the road, it will pop loose and catch on the safety position...
this is about to drive me nuts!! so far i have tried the following to correct the problem:
*adjust the "eye" loop all the way in and out 1/2 turn at a time - no change...
*adjust the rubber bumpers up to better support the hood - no luck here
the new cable seems to be really tight when compared to other chevys. i have thought that possibly may be too short and put a pre-load on the latch thus giving way to my problem.
My bro has a 78 3/4 ton and I have a 77 parts truck. They both have no release in the cabin, just a handle that you pull up front. My grill is cut out (factory styling, no mods) that your hand fits nice up in there and pops the hood. If interested, you can have the latch and if needed, the grill(light grey in color) very cheap.
I had the same problem with my 79 Jimmy. I think the LMC cable is a little too short. I adjusted everything that I could and ended up back where I started. I just slam the hood real hard and so far it is holding. Mine was a pain because I have a fiberglas hood.
If the hood had been off you can look at the bolt marks on the hinges and see if the hood didn't get put back on in the same spot. If so, you should re-align the hood so that all the gaps are the same and the height is right at the back edge. Then adjust the latch. I'd make sure the latch was sloppy though so you don't end up not being able to get the hood back open.