Hold all calls, ...we have a winner!!! (BOP) Buick, Oldsmobile, Pontiac plus GMC / Chevy trucks and vans.
No such thing as 5 on 5 sssooooo it is either 4 1/2 on 5 or 5 1/2 on 5 the 49 lincoln has 5 1/2 on 5 just like the ford F150 and the 80 lincoln has 4 1/2 on 5 if you read Jegs or Summit there is a chart to show how to measure wheel studs.....
Yes there is There are a lot of ford rears with the 5 on 5 bolt pattern. I have a few laying on the floor right now. 64 T-bird, 78 Lincoln. and a few other that I am not sure what they are out of. I'm not sure about the 57 Mercury. But if you have the rear measure from the outside of the one lug to the center of the lug across from it. That will give you the bolt pattern. Or measure center to center. on the 5 bolt pattern. The 4 1/2 will measure 4 1/4, The 4 3/4 will measure 4 1/2, 5 will measure 4 3/4 and 5 1/2 will measure 5 1/4 6 lug and 4 lug just measure center to center.
A friends 56 merc had the 5X5 bolt pattern,either 52 or 55 was the first year for that bolt pattern. The 5X5 was used in the mid 70s on the big cars.
You are TOTALLY mistaken............I have a '57 Merc axle ***embly, pulled it myself, and two, count'em, two, Edsel 5 on 5" BC rear axle ***emblies. Other posters are correct that several other Mercs and big Fords/Lincolns had that pattern too. How come you were soooooooooo certain you had the market cornered on that info? That 'no room for error in my opinion' is just a little annoying when your opinion is incorrect. Ray