Some clarification is in order here!
First, the V-730 is NOT
an "Overdrive" transmission. The ratio in third gear is the same as an HT-740 - 1:1.
Where the misnomer of overdrive came from is in the bevel gearset's
ratio, which in 99.9% of the V-730s is 0.875:1. If you look at a cut-away drawing of the 730, you'll see that the bevel gears are located between the engine and the torque converter, actually before
the transmission gearing.
This is the same set-up as the Manual transmission, except that the manual uses an 0.808:1 ratio.
Stock rear axle ratio for the 4106 is 4.125:1. 4.375:1 was optional, but very rare.
final drive ratio is equal to the following formula: (transmission gear ratio) x (bevel gear ratio) x (final drive ratio).
For a stick shift in 4th, this equals (1:1) x (0.808:1) x (4.125:1) = 3.333:1
For the V-730 in 3rd, it's (1:1) x (0.875:1) x (4.125:1) = 3.609:1
Supposedly there were V-730s built with a 1.04:1 bevel gearset, but I've only heard of one in over 25 years in the bus industry. Rarer than hen's teeth.
Taller tires on V-730 coaches (11R24.5s, usually in the 470 - 475 rev/mile range), will bring the coach back to almost the same top speeds as a stock stick shift w/ stock rev/mile tires (495).
HTH. . .
How do you tell what type of final is in a V730? Does most popular mean most common, or most desirable? Mine seems to have plenty of top end but I do not know what my rpms are. I hope to have a tach sometime in the future.