Hey neighbor.
I just went on a big 'quest' to replace the old 2 piece rims on my 8 lug chevy. I went to a place with take off wheels, 3x, but couldn't find a wheel to fit mine. Then the cat told me to look for 81-91 chevy 8 lugs which he said should work. I got the ones on my truck at C&M in garland near my home for 475, with big 245 16s (used but nice - and not matching

) on em. That's $5 less than new tires for the Lincoln I used to have with no wheels. As I am in a neighborhood with older vehicles, the shop had new steel chrome wheels ready to go. I would think 6 luggers would be even easier to find.
so..2 suggestions:
1. Call LMC and measure yours and tell them to measure theirs and see what they tell you. After a few trips, I would just call in the measurements.
if that don't work
2. Try the local wheel shops or even a boneyard. Tell them you have an older truck and usually they know what to give you. I then write them a check take the wheels home and if they don't work, come back and tear up the check.