Hey everyone, I'm wondering how difficult it would be to swap in a tranny with overdrive in a 2002 blazer that didn't originally have it. I have to replace the tranny in my blazer and I can find alot of them with OD, but nothing decent without it and I was thinking if it isn't too much work I would just take one of them with it and throw it in, and maybe get a little better mileage as well. Anyone have any idea what would be involved in doing this? I'll be getting the tranny from a salvage yard, so I can probably find any other parts I would need to convert it there, but I'm not too sure what parts I would need. Thanks for any help you can give me.

 

Are you talking automatic? All of them for your model year came with OD. I don't know how far back you would have to go to find one without OD.

 

As stated by rriddle, your stock tranny has OD. To be a bit more specific, it is a 4 speed automatic transmission with overdrive very commonly and correctly known as the 4L60E found in a vast number of rear wheel drive GM vehicles from the mid '90s to present.

 

Ah, ok, I haven't driven that truck in like 10 months and I kept seeing ones listed on Car-part.com and some say AOD and some just say that it's a 4spd so I was under the impression there were different ones and I didn't recall having 1 2 3 D and OD on the column like other vehicles I've owned so I thought I didn't have OD, but I'm probably just mistaken. Yeah, it's an automatic, so I should be good with any 4x4 AT for that year then?

Also is any tranny from 96-04 compatible? And if so, are certain years better than others? I know they get updated as years pass sometime, and if I can throw a more dependable or better performing one in, I might as well. Thanks for your help guys.

 

Quick little lesson on the 700R4/4L60/4L60E transmission GM installed in all rear wheel dirve vehicles since the early '80's. This includes pick up trucks (fullsize and S10), Vans (fullsize and Astro), Blazers, Tahoes, Suburbans, Corvettes, etc. ALL rear wheel drive vehicels have the 700R4/4L60/4L60E tranny since the early 80's.

The transmission is a 4 speed, as in 4 forward gears, with Overdrive (4th gear is overdrive) there is also a torque converter lock up, which increases gas mileage at higher speeds. Torque converter lock up is not another gear.

Your shift column either shows (1,2,3,D) OR (1,2,D,OD) its the same thing. 1st gear is 1, 2nd gear is 2, 3rd gear is either 3 or D, and 4th gear is either D or OD, depends on which column indicator you have.

There were initial problems with the 700R4 in the early 80's, however by 1985 all those were fixed. In '93 GM started installing the 4L60E, electronic version of the 700R4. In '95 or '96 GM changed the case design and made the bellhousing removeable.

The best year to use is one year above and below your current year, except if your model year is the change year.

The simplest way to find out what years will work is to call a salvage yard and ask them. They have all the cross references numbers and can tell you which model years and which vehicles and will sell you one. If it doesn thave a 30 garuntee, dont buy it. If you do go with a salvage yard tranny, buy a quart of tranny shock, new filter kit, new dipstick tube gasket, new pump/torque converter gasket (lubricate seal with tranny fluid before installing torque converter), new output gasket or new t-case input gasket (lubricate seal), tranny drain kit, auxillary tranny cooler kit, can of Kleen to clean your old tranny lines out, and 10 quarts of new tranny fluid. Save the reciept, you will be returning tranny fluid.

Do all that and even that used tranny will last a long time, provided it was good to start with. Easiest way to tell if hte tranny is good, look and smeel the tranny fluid, red (not brown or black), and no burnt smell.

 

Great info Hanr3, thanks a lot for taking the time to set me straight, I appreciate it, it all makes much more sense to me now.