In June 1941, Willys delivers 1500 units to the military of their Willys MA. After vigorous testing, work began on improving the model which would be known as the Willys MB. The production of this model started on the 19 November 1941, and was later known as Slat grill Jeeps. I say later known as Willys changed the design to what is now known as a stamped grill. A slat grill was several bars of steel welded together, but this was proving to be expensive , hence willys switching to the stamped grill design which everyone is familiar with and was a Ford design.
By the time slat grill production had ended in early March 1942, 25,808 of these jeeps had been manufactured. There are several differences between the Slat grill and the standard Willys MB, so these are the main differences. Slatties as they were nicknamed, had no gloveboxes, until late February 42, when the last few had them put on. (these jeeps are very rare). The fire extinguisher was also on the right hand side in the footwell, although this was changed to the left when gloveboxes were introduced. No blackout lights were on the drivers side fender. 
The wheels were not “,combat rims”, just one piece, manufactured by Kelsey Hayes. There was no jerry can holder fitted to slat grill Jeeps, and the back panel had the manufac turers name stamped in it. (both Willys and Ford adopted this practice), this ceased around May 42. There was rubber bonnet blocks on the hood, this continued until May 43. No trailer sockets were on slatties, and the exhaust muffler was round, not oval. 
The fuel tank sump was square, except for Canadian contract jeeps (2000 units). The pintle hook had no eye rings on either side of it, and there was no support bracket for the spare tyre. The most noticable thing on a slat grill dashboard is the fuel gauge, except it dont say fuel, it says GAS. In the engine compartment, you have the “pancake style airfilter”. The battery tray is a two piece, and on the engine, there is no “willys” name cast on the cylinder head. The fuel tank has the small nozzle for the filler hole. On the underneath you will notice the propshafts are skinny, and not the standard “fat” type, and the gear box has only one filler plug. So those are the main differences between a slat grill and the later stamped grill jeep. A slat grill does command a higher price than a standard MB due to their rarity, also those special slattie parts can be harder and more expensive to come by. Around 2000 slat grills , in various states of repair survive to this day. Slat grill Jeeps can be a shrewd investment, with values seen to be on the rise, but can be a difficult restoration due to parts, which are out there but scarce. A well restored, looked after slat grill is a real head turner, but there are people out there who dont think a slattie is a proper jeep because it “looks different and doesnt have a jerrycan on it”. Yes i have had it said to me. So there are the main differences, although there are several more, like holes drilled in different places etc,etc, but these are petty differences, mainly for the purist.
Written by Mark Jesic
