Im sorry accidentally hit “solved” before and I can’t edit-

Sequoia 2wd, mileage right at 300k. I have had it for 10 years and I can not buy anything else right now. I’m a single mom and keep being told different things about it, and I’m not sure who to trust - maybe someone can help? 

1. When I had the drive shaft fixed and rear bearing pack replaced I was told it needs front wheel bearings and valve cover gasket. The mechanic can not figure out why it rumbles hard at about 37mph if accelerating, maybe like when you hit the rumble strips on the side of the road. His scanner doesn’t show anything.
It is leaking minor amount of something (only noticeable when it rains and a rainbow like spectrum runs across my driveway).  But it’s not using oil. And there is a burning smell when you get out after having driven it but it doesn’t run hot.

Has anyone experienced this?

2. And at almost 300k miles two shops have said replacing a transmission is a lot of $$ for such high miles when the engine could go out too.  

I’ve watched Scotty videos that make me think it may be worth the transmission cost if that’s even the problem. Or I can just drive it til it stops. What do you guys think? 

Thank you in advance for any help!!