I need to replace my 98 cav auto 4spd tranny due to a broken case. According to the Gm factory service manual the code break down is 8WK 618wkr j vsx6 And the trans I am looking at is 0WK 610wkr j ????. (cant remember last 4 didgts) I under stand that 0WK is model & year and 61 is 4T40E but is it critical that any other numbers match when doing a swamp? Thanks for your help ! Handi

8WK 618wkr j vsx6
0WK 610wkr j ????

1st digit = model year (8 = 1998, 0 = 2000)
2nd, 3rd = model (WK)
4th, 5th = transmission (61 = 4T40-E)
6th-9th = broadcast code (8wkr, 0wkr)
10th-13th = serial number in Base Code 31

I don't know how to check the gear ratios from those numbers tho. There's a listing in my Hydra-Matic manual of the available gear ratios... based on teeth. 6 different ratios. However, I don't think J's had options on that... they were all 32/38 chains with 3.29 final drive and 3.91 effective overall ratios.

Assuming it's from a J-car... probably be just fine

John,
Thanks for the input. My manual showed 3 final ratios but they were all very close, dont have it in front of me at the moment. The replacement tranny is out of a 2000 cav 4dr while mine was a 2dr. Thats the only difference so I will go ahead with swamp. The GM tech at the dealer ship thought I would be okay also but even he wasnt sure about what the manual called broadcast code or serial number in base code 31 meant. Thanks again and I will probly be back for more info when I start the swamp. Handi