Tcupp Posted April 21, 2012 Share Posted April 21, 2012 I found the rear end code stamped on my 71 Monte. I looked at the tech section on the codes and could not find the last letter. Here is the code KDC 209 A. Does anyone know what the A is? It's a 12 bolt and I know it is the original rear end. Thanks Quote Link to comment Share on other sites More sharing options...
LS5 Posted April 21, 2012 Share Posted April 21, 2012 This is all I got for now hope it helps... Darren. The rear axle identification code consists of at least a two letter prefix indicating the gear ratio, a letter for the manufacturer's identity, and three digits indicating the day of the year from January 1 and other codes as necessary. The identification code should be stamped on the bottom or font of right axle tube either adjacent to the carrier housing or about 8" - 10" inboard from the backing plates. The particular engine RPO code is listed in parentheses as found on buildsheets. Example: RUC064(1 or 2) decodes to RU ~ 3.31:1, C ~ Buffalo, 064 ~ day of year starting with January 1 (the 64th day being March 5), 1 or 2 ~ shift (if present). See bottom of page for photo examples. Casting Numbers: 12-Bolt Casting #3969278 10-Bolt Casting #3969277 The casting numbers/letters on rear end housings may have either a prefix or suffix of "N" or "NF" and no reason has been found yet why they may have one or the other. Gear Ratio - First & second characters Prefix Axle Ratio CF 3.31:1 ~ 12-bolt Positraction CH 2.73:1 ~ 12-bolt Positraction (L48/350-4, LS3/330-4)* CW 3.31:1 ~ 12-bolt (L48/350-4)* GA 2.56:1 ~ 10-bolt (L65/350-2)* GB 2.56:1 ~ Positraction GD 2.73:1 ~ Positraction GF 3.08:1 ~ 10-bolt GG 3.36:1 ~ 10-bolt (base L6)* GH 2.73:1 ~ 10-bolt (L14/307)* GI 3.36:1 ~ Positraction GN 3.08:1 ~ 10-bolt (L14/307)* KD 2.73:1 ~ 12-bolt (L48/350-4)* RU 3.31:1 ~ 12-bolt (LS5/454)* RV 3.31:1 ~ 12-bolt Positraction (LS5/454)* RW 4.10:1 ~ 12-bolt Positraction(LS5/454)* Rear Axle Assembly Plant - Third character Code Assembly Plant C Buffalo, N.Y. G Detroit Gear & Axle K McKinnon Industries (GM of Canada) W Warren, MI. Assembly Day - Day of the year, 000...365 Shift - 1 or 2 (or Day / Night) if applicable Quote Link to comment Share on other sites More sharing options...
alex's72fgmc Posted April 22, 2012 Share Posted April 22, 2012 its a 2.73 :1 ratio rear end look in the tech info section for the rear axle decoding info i wrote up a while back covers all firsst gen montes alex Quote Link to comment Share on other sites More sharing options...
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