PREFACE: Forgive me, for I have sinned! Twenty-four hours ago, I posted this thread under a dumb, ill-thought-out title. In one day's time, and given the large amount of difficult-to-find information contained herein, only 110 folks have even taken a peek (with ONE reply), whereas the "Engine Paint" thread has garnered three times the viewing. So, I have learned a HUGE lesson. Continuing-on...NEW title, but... "Second verse, same as the first". After this, I will bore y'all NO MORE! 
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1939-1948 FORD/MERC Wheelbases, Torque TUBES, Front WISHBONES
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FORD Wheelbase Dimensions:
1939-1940...…..112"
1941-1948...…..114"
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MERCURY Wheelbase Dimensions:
1939-1940...…..116"
1941-1948...…..118"
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Karl Wescott has been so kind as to send his otherwise-unobtainable dimensional prints depicting the first iteration of the shorter Mercurys (1939-1940) along with their comparable year Fords, as well as the subsequent longer wheelbase Mercurys (1941-1948) and their comparable year Fords. The differences are MANY between the Fords and Mercs.
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1939-1940 Ford & Mercury
1939-1940 MERCURY
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1941-1948 Ford & Mercury
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Some FORD vs MERCURY Facts:
1939 and 1940 Mercurys had their own unique BODIES.
1941-1948 Mercurys began sharing common BODIES with Ford cars.
Mercury Wheelbase dimensions ALWAYS exceeded Ford Wheelbase dimensions in any given model year by 4" during the 1939-1948 era.
Fords and Mercurys utilized FOUR different wheelbase dimensions throughout the 1939-1948 I-Beam and Torque Tube era....note above!
5"-Wide wheels were available for MERCURY at least in 1941.
The "ODDBALL" one-piece Mercury driveshaft/pinion lasted ONLY 1939 and 1940.
Ford and Mercury REAR axle assembly WIDTHS are the same for like model years, as suggested by axle shaft part number comparisons, Ford/Merc.
1939-1942 Ford & Mercury SERIAL Numbers were issued independently of one another, actually based on full-size V8 engine cubic inch ratings. One should remember that transmission/engine assemblies were initially stamped with a serial number when produced, then distributed to vehicle assembly facilities. Upon the assembly's installation into a new vehicle, the serial number stamped on the transmission was hand-stamped into the vehicle frame rail. Thus, a NEW Ford or Mercury was born.
1946-1948 Ford & Mercury engines became identical cubic inch-wise and in horsepower rating. Since the 1942 Mercury engine was of a larger 239 cu. in. displacement (Ford was 221 cu. in.), Mercury's numbering system began with a "99A-" prefix (Ford prefix was still "18-"). After the War in 1946, 239 cubic inches (a Mercury holdover) was standard in Fords and Mercurys. ALL engines then received the "99A-" serial number prefix. Thusly, during 1946-1948 production years, ALL Fords and Mercurys SHARE a COMMON prefix in their automobile serial numbers. You cannot distinguish between Ford or Mercury by serial number during 1946-1948 production.
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I-BEAM Axles:
1939-1941 Fords & Mercurys shared "78-3010-A" I-beam axles.
1942-1948 Fords & Mercurys shared "21A-3010" I-beam axles.
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Front WISHBONES:
Four different Wishbones were used on Fords & Mercs, 1939-1948
1939-1940 Ford......"78A-3405"
1941 Ford...………..…"11A-3405"
1942-1948 Ford......"21A-3405"
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1939-1940 Merc...…"99A-3405"
1941 Mercury...…...."11A-3405"
1942-1948 Merc...…"21A-3405"
NOTE: 1942-1948 Ford & Merc used SAME "21A-" Wishbone, but Mercury's 4"-longer wheelbase necessitated the use of a 4" wishbone ball adapter/extender which bolted into Merc frame....picture below!
I discovered one more interesting measurement comparison between a 1939 FORD and a 1939 MERC Wishbone. Note that '39 & '40 MERC use Wishbone "99A-3405". '39 and '40 FORD use Wishbone "78A-3405".
rockflameasured between the center of his '39 MERC wishbone ball, straight forward to the center of his I-beam axle.....40-3/4".
Kube measured between the center of a '39 FORD wishbone ball, straight forward to the center of his I-beam axle.....40-3/8". For some reason, MERC in 1939 decided they needed a "99A-" wishbone that placed the axle 3/8" farther forward than a "78A-" FORD wishbone would have.
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Torque TUBES:
1939-1940 FORD T-Tube.....70"
1941-1948 FORD T-Tube.....72"
1939-1940 MERC T-Tube.....73-3/4" (approx.)
1941-1948 MERC T-Tube.....72" (Update)
'39-'40 Mercury MERC T-Tube NOTE: rockfla had a difficult time measuring the exact length of his '39 Merc T-Tube as the forward end of the T-Tube is very confined above the crossmember, plus the T-Tube bell is obscured by the clamshell assembly. Nevertheless, '39-'40 Merc T-Tube is ALMOST 4" longer than Ford counterpart.
The '39-'40 Merc T-Tubes ARE in fact, constructed with what appears to be a 14-15 inch sleeve in the center.....possibly a two-piece, fabricated tube. Reason unknown!
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Many other differences between Fords & Mercs left to verify. This compilation constitutes a concerted beginning.
1941-1948 MERCURY T-Tube dimensions are still unknown to this document.
MANY Thanks to: "rockfla", "JSeery", "rotorwrench", "Kube", "deuce_roadster", "Mac VanPelt Informational Website", "35ragtop", Karl Westcott, and probably others I'm sure, in preparation of this compilation!
Dick D (DD)
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