Just installed the gears last night, changed from 3.42's to 3.90's havent picked up the truck yet, but can i drive the truck for a day or so with out programing the computer on the new gears, i would like to break them in before retuning it, what do you all say? ALso i have heard doing some heating cycles for break in how does that work? I just wanna drive the truck now,lol.

 

ya need to do a few heat cyles on them before going crazy. lemme know what difference the gears make. i am getting ready for the swap myself and will prolly go with the 3.90s also.

 

yea just do a few heat cycles I the tune isent going to do anything but help your speedometer

 

drive like 15-20 miles (max around 50 mph), stop and let them cool down. Then go 25 miles (or around there) at 70 and let them cool down. After that, you should be good but don't romp on it till after 500 miles. At the 500 mile mark, I would change the diff fluids and pull the cover to check for metal shavings.

and you should be fine driving without the pcm reprogrammed. Your mph will be way off and the abs sensor light will probably come on.