I recently purchased a 1989 brougham. It has the 3.23 rear gears (rpo code GU5). Standard rear gears for 89 was 2.93. Im trying to figure out if my car has the trailer towing package or the heavy duty ride package or maybe just optional rear gears but cant seem to figure out what the rpo code for either is. Anyone with a late eighties brougham with trailer package can provide me with rpo codes to compare would be great. Any other info that might lead to an answer greatly appreciated.

They had 2.93 in 89??? Are you sure?

Well, I purchased a 1989 cadillac sales brochure and in the brougham section under specifications it says rear axle ratio is 2.93:1 standard. Were you under the impression it was something else?

Well yeah. I was under the impression that GM created the 2.93 ratio for the LT1 cars in 94 for some reason, as the towing package wagons also run 2.93.

Maybe GM had it all along as a special ratio for just the old FWB and decided to resurrect it when they went to the LT1 generation.

Well for late eighties brougham owners check the rpo code for axle ratio. It will probably read one of the following, GU1=2.41 GU2=2.73 GU4=3.08 GU5=3.23 GW9=2.93 I initially thought that standard gears in late eighties broughams would not have been 2.93's either until I read the original sales brochure. Maybe its wrong.

Yeah I was aware of everything except GW9 before 1994. How widespread was the use of it? Maybe just the FWB? I am not aware of its use in ANY B-body, wagon or sedan, before 1994. For example, my dad's towing package 91 Olds CC was 3.23. Non towing package I think was 2.73. Base sedans were 2.56 and even base wagons, Fleetwoods and RMs (and probably Caprice's) in 94-96 were 2.56. Then 3.08 was used in many places before and after 1994. Even 3.42 (91-93 9C1) and 3.73 (93 FW towing). Just haven't seen 2.93 anywhere.

How do you check and see which rear end you have?

Find your SPID label. Trunk lid probably. GW9 is 2.93.

Dopestar, Id be curious to know what you find. Post it when you know.

Yeah it's the 2.93:1. Can someone explain what the ratio means?

It means that for every 2.93 rotations of your driveshaft, your tires will turn once. Lower gears (higher numbers) improve acceleration at the expense of higher RPM at high speed. Higher gears (lower numbers) kill acceleration but lower cruise RPM. Of course, this doesn't factor in possible 1st gear and OD ratios in the transmission...

Wow so 2.93 was used before 1994 in the FWB. Is that it?

yes they did. i also have an 89 with the 2.93 rear. shame its so slow off the line.

I don't think 2.93 is that bad. I think the 307 is hurting you more than the gear. My 95 will spin the tires no problem (2.93 also).

Thats why with the 307 the 3.23's are prefereable. Not much difference at highway speed but noticeably more oomph off the line. Im still trying to figure out though if the 3.23's were available as standalone option or only tied to tow package. Also I cant for the life of me find any info on what the tow package or heavy duty ride RPO option codes are or what additional equipment was included other than the rear gearing. Brochure states that tow package is designated to 5000 lb's but I dont see a gm RPO code that matches that. Maybe all it included back then was rear gearing and shocks thus no seperate RPO code. Any more insights appreciated.

According to a guy selling an 88 brougham deElegance on ebay the rear end may have been upgraded by the inclusion of the deElegance package. Not sure of the validity of this but it might be an answer.

The D'elegance package was an extra $1,800.00 and includes the special tuft and rolled seats, and different rear end ratio.

Well that makes sense, because the 93-96 Fleetwoods got a rear end upgrade with the Brougham package. 2.56 was standard and 3.08 with the 93 Brougham or 2.93 with the 94-96 Brougham.