looking for oil filler cap

recently purchased a 1988 chevy C/K 2500 4x4, 350 with centerbolt heads, and i need an oil filler cap, went to dealer and they told me that model truck only came with a 4.3 that year, and none of the filler caps they had would work. was wondering if it could be possible an engine swap was done and the 350 is out of a van, and has a filler tube that uses a grommet? there are no slots or threads for the screw in type caps, and the push in style are too small. any help would be appreciated

i've never seen any like that. what happens if you remove the grommet? are you sure it has gm valve covers? if not you might have to buy some.

didnt have a grommet in it, just a hole, say 2" in dia. with a lip about 1/4" high, pointing down toward the top of the head that goes around the circumfrence of the hole, no slots, grooves, threads, anything. and they are gm valve covers

The dealer must have smoking something when you went to him, according to the autozone website gm put 350's in 90% of the 2500s that year, when you think about it, it would be kinda useless to have a 3/4 ton with a v6

you wanted chrome valve covers anyhow..now you have an excuse.

yup JW, i guess i do, lol. still havent been able to find anything remotely close

I did an engine swap in my S10 with a '90 350 out of a van and I have the same problem. I must have thrown away the filler tube from the van because it's so long. All that's in the hole is a stiff rubber grommet that basically just makes the hole smaller. When I pul out the grommet- it's just a round hole with no slots or threads. Wierd huh?

very weird, but gives me something to try, think i'll check the dealer and see what they can come up with