I'm sure the frames are the same. 114" and 118".
Up on the front of the frame there are two sets of holes that made the different wheelbase.
I think the only difference was in the door length.
But I've been wrong before....once.
Merc should be the same as ford.

Have a look at this.....

A new branch of dealers sold Mercurys, imported Lincolns, and a new line of Mercury trucks. By 1947, Ford of Canada had 1113 dealers, 353 of which were Mercury-Lincoln outlets.

Because Ford was in the low-priced field, it was more popular in Canada than the medium-priced Mercury. So that the new Mercury dealers could get a piece of the low-priced action, a smaller lower cost Mercury line emerged.

This new Mercury needed a name to set it apart from its larger sibling. So, it bore the title Mercury 114--a reference to its Ford wheelbase in inches. Therefore, the larger Mercury was known in Canada as the Mercury 118, its wheelbase length.

This new car was really a Ford, but with Mercury-style grille, tail-lights and trim. For the grille to fit onto the Ford front, it had a totally different frame around the vertical Mercury bars. Below this grille was a chrome section with two long openings which substituted the lower air-intakes of the Mercury 118 design.

A unique point on the 114's grille was an embossed head of the god Mercury just below the "Mercury" nameplate. Another 114 grille feature was the lack of E-I-G-H-T spelled down the middle.

There were small round parking lights below the headlights of the Mercury 114. The shape and location of these lights bore no likeness to either the 1946 Ford or Mercury 118 parking lights. For 1947 and 1948 however, Ford used the Mercury 114 type parking lights.

Chrome trim on the 114's fenders consisted of double strips which were more like the 1942 Mercury than the 1946. Because of the pucker on Ford's front fenders, these chrome strips did not come all the way forward to the headlight rims as on the 118.

The Mercury 114 used tail-lights like those on the 118. But there were no chrome strips across the trunk door, which the 118 had. Instead, there was a chrome embellished trunk handle below the license plate bracket. A Mercury nameplate appeared above it.

Ford V-8 engines powered the Mercury 114. Displacement started at 221 cubic inches. After June 1946, 1/8th inch was added to the bore for a 239.4 cu. in. displacement. There were some unexplained discrepancies about output. Horsepower ratings were in the area of 93 to 100, unaffected by displacement changes.

Like Ford, the Mercury 114 came in DeLuxe and Super DeLuxe editions. DeLuxe offered Fordor Sedan, Tudor Sedan, and business coupe. Super DeLuxe (aka Mercury 114X) added a 6-passenger Sedan Coupe, convertible, and station wagon.