The G50/20 or 21 is probably what I am going to end up getting and have the first and 6th gears swapped out for a 2.81 and .656 respectively. Of course I have no idea what that would cost and probably will not be able to afford it right off the bat. I have an email into GBox so well see what they say. Is the one in the picture the one you bought? Where did you acquire it from?
When I spoke to Erik about the feasibility and cost of swapping the gear sets, he mentioned that a swap of first gear is more pricey than the others because the gear itself is welded to the shaft. So there is more cost involved as far as that goes. But if that's not an issue, then it makes sense to make the switch.
I know in my 5 spd (G50/03 on an LS2), First gear is pretty much used only for pulling the car into the garage, or maybe going up a trailer ramp.
In my mind, it doesn't make a lot of sense to use 1st out on the streets, since you'll be shifting again in less than 100 feet.
4th and 5th have been switched in my gear-box, to give better ratios at cruising speeds. (between 70 & 80).
It seems that the quote for changing 5th & 6th in a G50/20 (6spd) was somewhere in the 2500 to 3000 range. If you add a 1st gear swap, you'ew looking at around 4000 to 4500. But I'm not sure if I'm remembering 100% correctly.
The gear box has to be set up to be run "inverted". Some people do this themselves, but I have Erik set mine up for me. It's not overly expensive to have done, but it definitely needs to be done.
And don't forget about upgrading the side plate to something that won't twist off when you apply the 400 or 500 ft/lbs of torque through your newly rebuilt gearbox. CMS makes a very nice billet plate for the Porsche boxes. I think it ran me about $450.00. I'm also running a transmission oil cooler, in order to help reduce the transaxle temp, and hopefully pro-longing the life of the gear box. $300.00 or so if I remember correctly.
It's not an inexpensive prospect.
I have around $12,500.00 in my (5spd) transaxle. If the Griffin, or Mendeola had been available when I bought mine, I would have probably gone that route... But they weren't.
I think if I were to do it all over again, (with a Porsche transaxle); I would buy one that didn't need the gear swaps. That limits you to the G50/50, G50/52, G64/51, and I think G96/96. These were used in the Turbos, GT2, and GT3 cars.
These all use a 9" Ring gear, where every other gear Porsche Gearbox uses a 7.5" Ring. The 9" Ring holds the torque of the LS engines much better than the smaller ring gears do.
Most importantly, (or at least equally important), they have gear ratios that are very comfortable when used with V8 engines.
They cost more on the front end, but after you buy them, you're only faced with a posible rebuild, instead of a rebuild and gear swap...
If you're planning on putting your car on the track
at all, you may really want to give this some thought.