'98 Explorer Popping/ Thud while in drive

[jtorzews]

Popping /thud/sounds like a misfire. When in park I can rev the engine up to to 4k fast/slow hard/soft with no issue. Engine seems fine. Put the truck in drive and under hard accel I get the pop or thud. Once or twice. Let off accel and it stops. Take it up slow and it's fine. Sounds like drivers side near the floor board. I tried a brake torque ( foot hard on the brake while giving it gas) and it also popped/ thud. No issues while in park. Scratching my head on this one. 5.0L AWD Limited

 

[92eddie4x4]

Is it an AWD vehicle?

 

[jtorzews]

Yes. 5.0L Limited

 

[92eddie4x4]

I'd bet that it's a stretched / loose chain in the transfer case. Just don't accelerate hard and bingo problem fixed. It's really not that hard of a job to do if you decide it's too annoying. Otherwise you can search the site to see if you can narrow down the problem.

 

[jtorzews]

I've searched the site with not much luck. I've seen post for a stretched chain and most felt that a chain would be a grinding or clicking sound. I do however, think the transfer case or something in that area would perhaps be plausible. Looking to narrow it down. Hoping someone here may have had a similar issue. Thanks for the reply.