CENTER TO CENTER BOLT PATTERN 48MM LARGE HOLE 20.5MM 4mm THICK NOT COUNTING O-RING This insulator will work perfectly on CT90's (1970_K2) thru 1979, don't forget the o ring it's sold separately (223H) see below WORKS FOR ALL ST90'S ALL CT110'S ATC90'S IF YOU NEED AN INSOLATOR THIS WILL WORK, BUT IT WILL BE ON THE CARB END, AND NOT THE HEAD END OF THE MANIFOLD This will also work for all stock TRX90s THE STOCK 1970 TO 1977 CT90 INSOLATOR 16211-077-306 IS DISCONTINUED, SO THIS IS WHAT WILL WORK. 300008 ALL FLAT ON ONE SIDE @ e ."O_RING" FOR CARB FLANGE TO MANIFOLD ALL_TRX90 CT90_78_TO_79 FITS_300008 INSOLATOR 1/22P (223H/1004E) THIS WORKS FOR THE BOTTOM OF OUR 215S MANIFOLD TOO 223H/1004E @ *ORING 27x2.0 1/20M (294G)ORING 27x2.0 294G @ THIS IS OUR 300008 NEW ORING TYPE INSULATOR ON A LATE CT90K1 CARB ???