Cast Iron (190-005) or Aluminum (190-005A) Versions Will Interchange. Some Units Use a Bypass Wire off Solenoid; Most Don't. For Best Results, Always Include a Universal "R" Terminal Cap or Solenoid With the Unit. The 16828 Gear Reduction Will Replace This (Which Also May Need to Be Fit With an "R" Terminal, if Necessary). It is Also Reported That the Delco 3630 Using an Accurate #217 Drive Can Be Used in Place of the 16224, If Desired.