Joe,
You're spot on about the late models & mods.
As far as the X mods...
Since Royal & Jimmy(Ray) created the class in Las Cruces a few years ago, there's been a grand total of 3 rules changes.
1.MSD boxes were legalized.We're buying used inventory to race with & most cars already had them.
Makes sense to use them...according to MSD they offer no performance advantage below 7000rpm.
They're optional...you don't have to have one.
2.Restrictor plates became required on all altered/hogged out Rochester carbs. Cost $44.00.
They effectively negated the $800.00 Rochester soup bowl carbs&$500.00 acid dipped intake manifolds.
3.The Holley 4412 carb (unaltered) was legalized.Cost $259.00
Ricks performance in Las Cruces has a table full of used pricey Rochester carbs for sale cheap...in case anybody wants one.
That's it as far as rules changing over the years for the X mod class.
Cubic inch limit (360)/compression ratio 9.5/1
EVERYTHING else has remained unchanged since day 1...
The powers that be down south are committed to keeping this deal affordable/competitive.
...as long as Fegan/all the other promoters stay on the same page & follow their rules...we're golden.