I no to use reg drive when pulling/towing with my blazer but my husband argues that reg drive is for everyday driving and overdrive is for highway/interstate driving as well as towing/pulling. I am simply asking for someone to tell me why, IN DETAIL, regular drive is used to pull/tow along with ne other examples of when regular drive IS or ISNT the proper gear and then IN DETAIL what overdrive is for and when it SHOULD or SHOULDNT be used. I just know what gear to use for things but I have no specific reasons to back me up. So if someone can give me the 411 on automatic transmissions and what it is exactly that is the difference between OD and D I would greatly appreciate it

 

OD can be used to haul trailers IF the trans doesn't shift from OD to D a lot.
Simple as that - if the trans can't handle the weight, air etc of w/e you're hauling it'll shift from OD to D a lot. This is not good for the trans & unless you have a tail wind, just leave it in D.
It all has to do with the gears, engine strentgh & weight behind you.
Mine can haul a 3200lb boat & trailer in OD at highway speeds (1800rpm or so, 3:42 gears @ 65-70 mph) but my trans is built up as well as the engine, aux trans cooler & that still depends on wind.
A head wind will push it to D & the rpm's soar after that, so I just put it there instead of the trans shifting from OD to D.
Heat is the worst enemy for a trans & shifting like that builds up heat.

 

there has been no upgrades at all to anything on my blazer so it is factory everything. how do i no if the transmission overheated or got hot? I drove it basically all day, more than normal, and there didnt seem to be ne issues that i noticed....its always had a lil whine when i first take off which i considered normal as every car ive ever owned had a lil whine that could be heard when taking off. What sort of things do i look/listen for to know if ne damage was done?

 

Pull the trans dip stick & look at it. It should be red or close to it, brown or worse = issues. Smell it & if it smells burnt you have issues.
You can drop the pan, swap the filter & refill it if either are present OR take it in & get it back flushed if either are present but it's costly.
Back flushing removes all the old trans fluid & I say that because the torque converter holds almost half of the trans fluid & doesn't drain out when you drop the pan. So you'll be green! - Recycling trans fluid, bad trans fluid possibly though.
It's a '95 are you sure when the trans fluid was changed last? 50K miles is normal for trans fluid.