Is the ax 15 transmission a good transmission would it work for a k5 blazer and help save gas?

If you put that tranny in your blazer you are looking at it blowing up pretty damn quick! the only thing i know they came in were jeeps and they sucked in jeeps too. your rig is a hell of a lot heavier than a jeep and your engine also puts out a lot more torque…in return that tranny wont last but maybe a week in your application. So dont waste the money for adapters to install it.

If you want to save gas in your blazer i would tell you to go find a TH700r4 since that will add the overdrive….

If you want to run a stick shift then the NV4500 is a great transmission…these are a bit pricier but are very popular with people into fourwheeling..SInce they give you good crawl ratio’s in the low first gear, but also have the overdrive for the freeway…

Since i dont know how your blazer is set up in the first place…its hard to say what you need to do to get better mileage.

So here’s a few things that will help…

figure out what ring and pinion you have…then run the tires that match the best….you probably have a 3.73 or 3.50 gears…so i would say running something like 265/75 15 would give you the best overall. running larger tires will take away your mileage.
depending on your year you need to add a fuel injection set up if you dont already have one…
and then just keep your foot out of it and drive like an old lady…

Basically what it comes down to is your rig will never ever ever get “good” gas mileage. The best you might get would be around 15-16….. But with all the stuff you will need to add you would just be better off finding a cheap rice grinder for a daily driver then keeping your blazer as a weekend toy.