I dont believe the LeSabre was ever sold new with L67. Never heard of one. Quite a few 87-89 LeSabre T-Type owners have trransplanted them same as many cars - Fieros, Grand Prixs, Reattas',FWD Regals., a Trofeo or two, maybe even an S10 or two. Kinda funny the cars he V6 were designed for - LeSabre, Century, Riviera never got the L67 except for the last Rivieras. Im glad they put it in the Olds LSS at least the LSS is a car that looks the part of performance. Im not sure if the 92 and on LeSabres evoke a performance sports sedan mood, maybe thats why they didnt bother. As the 86-91 2dr. LeSabres being my favorite of all H body cars, I have found the appearence of the 92 and newer LeSabres kinda disappointing, its a nice car and not ugly, just not stunning like its predessor. The LS in my user name is for LeSabre not any of the various LS model versions made over the years. So please dont misunderstand me but I dont know of many of the old LeSabre owners talking much or hoping much for a newer LeSabre. They need to change that rear roof line and the rear quarter panels, its way to reserved looking.
Gas milage, I doubt there is much difference. The higher final drives dont work well here in our hills. We get better milage and drivability if we leave them in D other wise they shift into overdrive and require lots of gas to keep speed up. Pull back into D and we can let up on gas. Also OD will coast up to 70-75 going down hill and requires way to much brake to keep the "serve and protect" people happy.