The Willys Slat Grille MB is a highly
collectible variant of the highly collectable
WWII jeeps. For owners wanting them
assembly-line perfect, they can be a very ad-
vanced restoration. Some of the early parts
are virtual unobtainium. Bob Malenfant can
testify to all this. He bought this ’41 after
it had a “motorpool” level restoration. That
means it was restored to a state similar to
what it would have been after years in ser-
vice, rather than assembly-line fresh. The
MB Slat Grilles left the assembly line with
a lot of unique parts, but when those needed
replacement, the motorpool troops would
have replaced them with later replacement
parts. Bob has been working to replace all
those later parts with more-correct ’41-era
MB Slat Grille parts, and this rig is now
getting very close to the original state. fw
AT A GLANCE
Vehicle: ’41 Willys-Overland MB
Owner: Bob Malenfant
Estimated value: $25,000
Engine: Willys MB 4-cyl L-head
Power (hp): 60 @ 4,000
Torque (lb-ft): 105 @ 2,000
Bore & stroke (in): 3.13 x 4.38
Comp. ratio: 6.48:1
Transmission: Warner T-84J 3-spd
Transfer case: Spicer 18 2-spd
Front axle: Spicer 25
Rear axle: Spicer 23-2, full-float
Axle ratio: 4.88:1
Tires: 6.00-16, NDT
Wheelbase (in): 80
GVW (lb): 3,125
Curb weight (lb): 2,315
Fuel capacity (gal): 10
Min. grd. clearance (in): 8.75
Approach angle (deg): 45
Departure angle (deg): 3568 OCTOBER 2019 FOUR WHEELER fourwheeler.com
Feature The Brass Ring
The engine compartment was very similar to
the later MB units but had some minor differ-
ences. The block and heads had some minor
differences and it was more like the Willys 441
car engine than a later MB engine. A true MB
engine has an “MB” prefix in the engine number,
and they started off at MB100001 just like the
chassis, but no effort was made to match the
engine and chassis numbers. In short order there
was a skew. Among the differences were the air
filter, dipstick tube, intake manifold, distributor,
voltage regulator, and radiator. When purchased,
Bob’s ’41 had a GPW engine. It ran well but he
wanted to get a lot closer to a stock slat-grille
engine in the details. Finding a correct slat-grille
engine is close to impossible, but he turned up
a Willys 441 engine and managed to find all the
other small parts. The 441 engine is identical ex-
cept that some of the numbers will be different.
Power was 60 hp gross and 54 hp net.Again, lots of differences here, among the least
subtle is the lack of a glovebox. This didn’t ap-
pear until about MB120697, so most slat grilles
did not have them. Less noticeable are the differ-
ences in the instruments, knobs, seat cushions,
seat brackets, steering wheel, and more.Another level of battle. In 1942, the Aberdeen Proving Grounds, one of the Army’s vehicle test facilities, got
hold of a German Kübelwagen captured by the British in North Africa. It was run against a slat grille in the winter,
and while the 4x2 Kübel did surprisingly well, it was no match in most situations.
Photo: U.S. Army