for the car in question, you could order the Sloan report and verify it is a factory 4 speed that way.
Auto and 4 speed values can be very different, usually 20-50% for a 4 speed, depending on the year and model.
Proper length speedo cable, slot for the parking brake cable in the crossmember, upper rear control arm braces
I would get the vin number and order a Solan Report. This is what I did for mine before I bought it. The Solan report did verify it was a 4 speed car only if you want to be sure! There were only 510 built. Who knows how many are left, but I am working on a 1970 Buick 455 4 speed registry. If you buy and it is a four speed please reply to this thread. http://www.v8buick.com/showthread.php?300142-1970-GS-455-4-Speed-Registry Thanks Ron
I cannot remember the number but it also has a specific carb number I think maybe 7040249 ? Very hard to find.
I'll check it out whenever I can haul it back to my house, hopefully tomorrow. Someone did try to snake me out, but money in person talks more than phone calls and empty promises, so better luck next time jabronie! Pretty stoked to call one my own! Now to work out all its bugs...
As poor as it runs, the only broken heart so far is my own. Never felt such a slow big block LOL. My brother's built Stage 1 when it was running on 3 cylinders is about an even match though! Now when I share some info about this car with y'all after I verify it, hopefully I'll break your hearts too...didn't want to show all the cards to you vultures. But this GS has some very unique things about it!