The stock relay is nothing more than a horn or lighting relay,an item easily gotten at any parts store. The solenoid is required for OD engagement,and as mentioned the lockout mechanism,the small lever on the tail housing,locks up the tranny so it operated exactly like a regular transmission.Best to have the OD locked out when doing burn outs,lol.
Like Cosmo, I run an OD tranny,a unit I put on a Saginaw car 4 spd.Instead of the dumb switch on the accelerator linkage,use a simple on off switch to bump the unit out or in OD at your command.I use the governor in the control circuit, but it's not totally necessary if ya always remember not to use OD in first gear.The reverse lock out is necessary,as the vehicle will not reverse if in OD cause of the overrunning clutch.
