I have run a Nash 4+1 for a couple of years at the track now after breaking numerous Super T10s
Box is great but from what I understand Richmond dont sell a straight cut non syncro version anymore (Shame on them) so the helical unit is the choice
As others mentioned whatch the ratios. With a 455 and a 3.25 first in the boxes it gets real easy to wreck some driveline parts (if you ever get it to hook up)
A 3.25 first and a 4.11 gear dont work!!!!!!
(30 ET street) no fault of the tyre
A 3.73 worked better and hopefully soon we will see what a 3.20 will do with a small shot
Look the the ratio of 4th with the boxes to determine your "real" drive ratio in top at the track. Mine is still 1.16 (5th is 1:1) which calcs out to around a 3.7 with the 3.20 which should be good
Starting line ratio will be 10.4:1 which will be alot more usable than the 13.35 or 12.1 we have used in the past. More gear slowed the car down so were going in the other direction
Working on going faster!!!