Just bought everything for 3.73 gears

zac_F71 said
Going off that calculator -

Automatic
in drive gear
3.91 gears since 3.73 isn't an option

29% throttle
75% converter efficiency
71mph = 4189rpm
YIKES!

24% throttle
75%
60mph = 3555rpm
Not as bad but still not good

I drive 30 minutes to work one way, it has a good cooling system, but I can't see it liking that kind of rpm for long...

Well we'll see I guess somewhere between 3,500 and 4,000 cruising rpm is my guess for 70mph

The reason the rpm's looked so high is you had the converter efficiency set at 75%. The junkiest converter ever built would normally be better than that. Reset it to 93-94% and you'll see a huge difference.

I had 3.73's in my car for a while with 275/60/15 tires and IMO their are pretty low for much highway cruising but everything is a trade-off. You want the car to be pretty quick out of the gate and you don't have a stroker making 500+ lbs ft. of torque you gotta have low gears.