Where'd 3rd gear go...

Ahhh, ok. I posted a while ago wondering why my tranny makes a noisy "whirr" 1st through 3rd but most noticeably in third gear. So I'm driving last night and I shift into third and it slips for a half second then catches. I thought it was my mistake so I forgot about it. It happend again in the morning, then again on my way to lunch. I knew something had to be up. After work, I was driving and noticed that there's NO 3rd gear. :( I can move the shifter into 3rd but it's just like neutral. I can move freely in and out without the clutch...

Has this happend to anyone before? Is there anything I should check externally that could possibly be the cause? The car has 124700 miles so I'm guessing it's just time for another tranny because 1st and 2nd "whirr" a little bit also. I'm thinking of getting a used tranny from a j-spec importer place; good or bad idea? Does anyone have any suggestions for a transmission shop in L.A. or a place to get a used tranny? Thanks in advance!

At least I can still drive until I figure out the best option. :p

I called one place and they said that the J-Spec trannys they recieve won't work in my '95 because they're from earlier SR20DEs. What cars do share a transmission with the '95 G20t?