3.08, GM's typical copout response to '90s CAFE MpG tests that were anachronistic in the 70s.What do they have factory?
The biggest bang for your buck mod for Fleetwoods, RoadMasters, and Caprices, including your Impala SS, has always been and always will be either:... maintaining highway drivability is important to me.
Gearing for more aggressive acceleration would impact that quite poorly ...
3.42 if you want to avoid driveshaft vibes and do lots of mostly highway driving
3.42 has a proven track record of statistically irrelevant highway MpG penalties
3.73 if you are ready to upgrade your driveshaft and do more city / metro / urban driving
3.73 has a proven track record of improving city / metro / urban MpG about as much as it costs highway MpG:
1-3MpG, depending on the driver and the qualiy of the pcm tune
Feel free to disagree, but 1Slammed96SS knows what he's recommending.
The ISSF has 13 years of collectively repeated and documented experiences which substantiate the above.
If not for the Great Data Mismanagement of Aug 2009, it'd be 21 years instead of 13.
If you are ever lucky enough to dare to test drive a B- or D-car with 3.42, you'll see for yourself:
More assertive gearing impacts drivability quite favorably.
Otherwise GM would not have used 3.42 for the Fleetwood 7000lb tow package (V4P).