This is what I found usimg my Chevy parts books.
Monte Carlo frame p/n: '78 470211, '79 14017671 (must use engine mount 14005699 on '78 models) (used on '78-'81 Buick 09, 69, 87), '80-'81 14013462 (superseded '78 & '79 p/n's) (used on '81 Regal), '82-'88 14103516 (use on '83 Olds W40
Hurst/Olds, '78-87 Pontiac except 35.)
Malibu (19, 27, 69) p/n: '78 461808, '79 14005602 (same note as Monte Carlo), '80 14017667 (must use '80 front park brake cable on earlier models, superseded '79 p/n) (Used on Buick 09, 69, 87), '81 14032514 (superseded '78-'80 p/n's.)
Note body codes:
2 door body: 27, 37, 47, 87
4 door body: 09, 19, 69
station wagon: 35
Looks like the Monte frame would be the one to work on a LeMans. Keep in mind that this is incomplete as I have not cross checked all GM catalogs for our cars.