No welding needed, these are hammer in tubes. Weld in ones require you to drill plu holes in your axle housing, these do not.
The Nitro Front Axle Sleeves have been designed and fabricated to protect and reinforce your axle tubes. The front axle tubes are known to be vulnerable to bending under light to heavy off-roading conditions. The Nitro Tube Sleeve Kit will take care of this problem.
Included in the kit are one short axle tube sleeve, and one long axle tube sleeve.