Those are 1st gear numbers. Your high speed gear is typically 1:1 unless its a Screamin Eagle version.

 

You read right.
They were indeed geared so that the total gear ratio between the engine and rear wheel, in high gear(5th)was 3.37:1. The trans was indeed 1:1 but the belt drive and the primary ratio together resulted in the 3.37 to 1 final drive. Actually the difference was in the primary, the belt sprockets were the same.
Rumor was it was done because the M-M injected motors simply didn't make the power the carb'd motors did, so they shuffled the gearing to help them out a bit. It ended up being approx. 300rpm difference on the highway.

You used to see people wanting to swap all the time. The go-fast guys wanted the 8% more power to teh rear wheel that the 3.37 offered, the high speed touring guys wanted the lower rpms that the 3.15 offered.

I had an '01 Ultra Classic with the 3.37 gear and I actually liked it that way, didn't mind the extra rpm at all, made the motor sound "free-er" than the WideGlide I had previously.
I even left it that way after I converted it to a carb.
Of course, I run my 6 speed bike in 5th gear unless I'm doing more than 70mph, which isn't often.

 

the original mm bikes came with 3.37 vs the 3.15 for the carbed bikes so they felt peppier. The efi eventually went to 3.15 in 2002 or 2001. I rode RK's for work thru 08 when we switched to Hondas and BMWs and the early bikes with 3.37 gearing were much better for giddy up. Lots of guys still convert 3.15 bikes to 3.37 because they get up and go.

 

Tdkkart, Do you know what the actual tooth count difference was in the primary?

So the reason the newer 6 speed runs 3000 rpm at 80 and the 5 speed runs 3250ish at 80 is more about Carb vs EFI and less about the transmission change to a 6 speed?

 

3.37 primary sprockets are 24/37
I don't remember what the 3.15 combo was, but there's a bunch of good info here: http://harleytechtalk.org/htt/index.php/topic,3006.msg27575.html#msg27575
Edit:, Found it, 3.15 was 25/36

The EFI vs carb gearing was the same after 2002 when the Delphi injection came out. There have however been 2 or 3 gearing changes since then, none of which had much to do with the 5 vs 6 spd, high gear ratio in both is 1:1. All the final drive ratio juggling was done in the primary and belt drive ratios.

I'm seriously looking at a couple options which will get me back close to the 3.37 ratio that my Ultra Classic had. It can be had with both a primary change, or a front pulley change, haven't decided which is best yet.

 

http://books.google.com/books?id=aS...NCEB4jlrAHJ-MiyDA&sqi=2&ved=0CGYQ6AEwAw#v=onepage&q=3.37 vs 3.15 harley&f=false

 

That is really interesting. Good links too.
Oh I see your edit: 1 tooth on each gear, how bout that.

 

So, if I wanted to head towards a 3.15 gear, I could swap out the front sprocket?