how do i determine which saginaw 4 speed i have in order to put a hurst shifter on it ?
thanks.

I'm sort of a saginaw guy.
Almost all saginaw cases are identical, whether used in Vegas, Monza, Camaro, etc.. I have always mounted the Hurst Comp. Plus on mine very easily by fabbing a homemade adapter plate. If you can temporarily position the trans in the car, use a 1/4" thick piece of steel plate, (about 4"x5") and bolt it to the 3 triangular-pattern 3/8 tapped holes. You will want to use recessed-style cap-bolts to keep the surface smooth and flush for the shifter.
Next, position the shifter where you want it and Vise-grip it in place while marking the 2 holes. The top hole will be 7/16", and the lower right will be 3/8". Drill and tap them and you are ready to go.
Be sure if you have a console to assemble it as well in order to determine ideal shifter location on the mounting plate. Also, be prepared to alter the Reverse shifter rod if using conventional Muncie linkage. (it will have to be made longer. Finally, trim the adapter plate so that it is no bigger than necessary for ease of install.