I can,t recall seeing the arrows on them but it,s been many years since I was around one of them but the SP (Special Parts) was quite common on tractors when I was working at the dealer.I saw tractors that were made for the army that came in for repairs but as I said don,t remember the arrows on them.

hello gauntjoh,your r2 4J970 SP was built in 1939 ,bruce oz

Your R2 is a 1940
All R2s were made for the government to meet specaul specs the first was the 5E and it was nothing but a 22 with weights added to track frames to meet weight spec for the military, the second 4Js&6Js were a gas version of the 3J&5J D2s with diff part to make it gas (pistons,head,feultank,manifold, and injector pump was replaced with mag.) Keep in mind that all crawlers made during wartime were made for military use and painted OD green, if a farmer was big enough or knew the right person they could get one but wasn't easy. For example Berglund Tractor covering Napa,Sonoma,Lake&Mendocino counties in Northern Calif. were only alowed to sell 2 D4s during the war. I have many wartime machunes and never have seen the arrow you mention.also in US that would not be a wartime machine but UK was in the was in 1940 so it is probably something for UK wartime machines

All the Js R2&D2 during wartime had SP because they all had a diff trans group that made the move faster the joke is it was to out run the bullits

If the R2 is a re-make of the 22, will the tracks off a R2 fit a 22? What other parts are interchangable?