Why do they still only have 4 speed transmissions in NASCAR?

[Mopar151]

2. Don't need no more...... - and a cost issue

The 4-speeds in current use are evolutinary copies of the Ford "top loader" (Jerico) and the Borg-Warner T-10 (Tex "T-101&quot One of the major differences is that these transmissions are available in a wide variety of ratio combinations - low gears range from ~3.5/1 to ~1.8/1.
Rear gear ratios are easily changeable as well - when DW mentions a "gear", he is talking about a removable carrier assembly, which holds the ring & pinion and the differential - 2 guys can change one in about 20 min. Available gears range from ~2.6/1 to ~7/1.
with these options available, it's pretty easy to get a gear combination that works for the particular track.

Cost is not a small issue - Quaife just introduced a new hi-torque racing transmission, to compete in the same market as the Jerico.
Jerico =$3500, Quaife = $14K Jerico has a 5 spd sequential for Grand Am & SCCA, goes for ~$7500.
How many transmissions does a Cup team have in stock, per car/driver? I'd bet a dozen...