I have seen some combinations of all of these John
The g50 is a ggod box but the ring gear cant be flipped, so the box has to be inverted, it works fine, but tge axles are below the input shaft centerline, and when flipped they end up about 5" too high.
The 915 porsche is a good box, the ring gear can be flipped, but the shifter rod sticks out of the rear, cable hookups seem a little mushy on this one, also the 930 box will work, but it is a 4 speed, and again the shifter rod sticks out of the rear.
I seem to remember a company called Vallios that made a side shifter kit for the 915/930 box, this works well, using a rod linkage.
Also, I have a friend who is using a 914 side shifter box out of a 6 cyl 914. It isn't as strong as the others especially in 1st gear, but there is a billet center section made for this box that really strengthens it, and the plus is that you can find it with a side shifter already installed, has good gear ratios top and bottom, and as long as you don't beat it up in 1st gear it will last. My friend has about 40,000 miles on his and going strong.
The whole problem here is the porsche clutch which can be costly.
There is a company in california that makes an adapter for most gearbox/transaxle combinations, Kennedy Engineering, you can also buy a kit with the adapter that comes with the flywheel to mate the gearbox to your engine using the clutch that would normally come in the vehicle
Good Luck
Phil
The g50 is a ggod box but the ring gear cant be flipped, so the box has to be inverted, it works fine, but tge axles are below the input shaft centerline, and when flipped they end up about 5" too high.
The 915 porsche is a good box, the ring gear can be flipped, but the shifter rod sticks out of the rear, cable hookups seem a little mushy on this one, also the 930 box will work, but it is a 4 speed, and again the shifter rod sticks out of the rear.
I seem to remember a company called Vallios that made a side shifter kit for the 915/930 box, this works well, using a rod linkage.
Also, I have a friend who is using a 914 side shifter box out of a 6 cyl 914. It isn't as strong as the others especially in 1st gear, but there is a billet center section made for this box that really strengthens it, and the plus is that you can find it with a side shifter already installed, has good gear ratios top and bottom, and as long as you don't beat it up in 1st gear it will last. My friend has about 40,000 miles on his and going strong.
The whole problem here is the porsche clutch which can be costly.
There is a company in california that makes an adapter for most gearbox/transaxle combinations, Kennedy Engineering, you can also buy a kit with the adapter that comes with the flywheel to mate the gearbox to your engine using the clutch that would normally come in the vehicle
Good Luck
Phil