96 jimmy 4x4 knock

i am in the process of buying a 1996 jimmy 4x4 with push button control. while test driving it i engaged 4 hi and upon acceleration a single knock comes from the front drivetrain somewhere and it seems it only happend when accelarating from a stop. it only happens in 4x4. wondering if someone could point me in the right direction.Seperatly the hazard lights will not shut off and when the car is on the gear indicator on dash blinks with them?? owner says it just started the hazard light stuff..my tranny went out in my other car and this is a clean jimmy for the right price just wanting to know if these are hard or expensive fixes...thanx a bunch your input is greatly appriciated.

i am in the process of buying a 1996 jimmy 4x4 with push button control. while test driving it i engaged 4 hi and upon acceleration a single knock comes from the front drivetrain somewhere and it seems it only happend when accelarating from a stop. it only happens in 4x4. wondering if someone could point me in the right direction.Seperatly the hazard lights will not shut off and when the car is on the gear indicator on dash blinks with them?? owner says it just started the hazard light stuff..my tranny went out in my other car and this is a clean jimmy for the right price just wanting to know if these are hard or expensive fixes...thanx a bunch your input is greatly appriciated.

Ask the seller if you can take it to your mechanic for a inspection of bad parts or if he will fix it before you buy it.

Let us know what he says.