Javenged1007

Thanks man!

Someone help me! In the process of troubleshooting my 2006 gmc Yukon Denali xl 6.0. It's my work truck and need to get it going asap but single income currently. So he it is 2006 GMC Yukon Denali Xl 1500. 6.0l AWD about 189000 miles First sign of problem, may not be related, but got home, went to put in park and could not get it into part. Kind of had to force it in place but gently. Drove fine next day and did not have issue after that. Few days later, took off at light and when shift into 3rd I think....it kicked really hard then revved up to 5000rpms. I got off the gas and it went back into gear. Drove it home about 10 miles carefully and if I lightly press the pedal it would advance. Got home and it made a weird wind noise drive side area. Check fluid, normal. Temp on gage for trans was at normal. Took around block and it goes into reverse no issue and then neutral then 1st, but when in 1st it seems the breaks are being pressed and its lags like crazy. Goes into 2nd hard then from 2nd to 3rd it slips. My question is where do I start? Is there something I should look for first? I was ase cert 22 years ago, so know my basics and do all my repairs but awd is not my cup of tea. I want to check my transfer case and see if there's fluid. Also going to do a visual inspection and check for any logical issues. Please any help would be greatly appreciated.

Might be a stuid question but what is the Difference between the Yukon Denali xl and the Yukon xl 1500?