I have a 1989/90 (title says 1990 door jam says 1989) and its the one with one 54mm nut instead of the 6 bolts, I cannot find any aftermarket lightweight flywheels with this bolt pattern, is there some adapter I need to buy or is my only option a custom machined one. I could find quite a few refurbished OEM flywheels like mine I just can't find any aftermarkets.

 

they all have the 54 mm nut. the 6 bolts bolt the flywheel to the rear counterweight (S5 or S6 automatic) you will have to use with them. ultimately, it's the large nut that holds the assembly to the engine though.