streettimetc

last night i started to hear a whine in 5th gear when i let of the gas. it sounds alot like a dog box. the car has 67,675 miles on it and the the tranny been serviced twice with redline mt-90 oil. i'm still on stock clutch and fly wheel. the car has been s/c for the last 40,000miles and had been through all the s/c problems.so if the tranny is on its way out i'm going to have to sell the tc. i'm going out to check the gear oil level now. so if any body any input on what the whine could be it would be verry help full.