The Polaris sleds are allowed the twin because it is Super Mod 1985 And older .
The twin engines are 1974-81 , so they fall in to the rules .
Further more twin 440 engines were available in 1973 TX 440 .
Super mod rules says engine must OEM for the brand , 1985 and older .
Also the Chaps can use a twin trail sled crankcase with a pair of 650 triple cylinders and make a 440 twin mod engine , or use a liquid 440 Chap engine and build an IFS super mod liquid 440 for Alexandia TLR ,Iron wood TLR, ER on modern weekend TLR
Think about it folks .
I agree ,bring Back the 1972-73 IFS Chapp's !!
Randy