99 front differential in a 97
 

Anyone here put a 99 front differential in a 97?

Re: 99 front differential in a 97
 

Why? There isn't a difference. In less your talking the NBS diff....

Re: 99 front differential in a 97
 

Should be a straight swap

Re: 99 front differential in a 97
 

The issue is that the 97 has a pigtail for the actuator and a pigtail for the 4wd engagement light. The 99 diff uses the mechanical actuator and has only one pigtail. Physically the differential bolts right up.

It took a few days of research and modifications to the wiring harness but I’ve got it sorted out.

Re: 99 front differential in a 97
 

Is the mechanical actuator aftermarket? Glad you worked it out

Re: 99 front differential in a 97
 

The mechanical actuator was stock 99 and up for this particular front differential. Chevy got complaints about the thermal actuators slow engagement in cold weather. To upgrade to the new style there is a service bulletin and a wiring harness from GM.

Re: 99 front differential in a 97
 

I know about the slow actuators, the reason for the aftermarket conversions. I didn't realize GM changed that in the last GMT400s. Took them long enough. Obviously only concerned with the next trucks being better in that function.

Re: 99 front differential in a 97
 

They had to make them quicker for the Autocrap t-cases. When in 4wd Auto, the t-case is in 2wd, but soon as it senses rear wheel spin, in engages the actuator instantly. Sorta. Best thing I did, was convert to an NP241.