bought a '88' 150 4x4. It has the 4.9 straight 6 and tranny problems. The gears are all over the place on the five speed manual and I just lost reverse! Pretty sure its a linkage issue. But, first things first. How can I tell which tranny is in this beast? I've seen about four different options that are possible.

 

it will be the m5od

 

Does that take standard gear oil? Whats the suggested weight?

 

It uses Dexron III ATF.
Some people use gear oil to hide/quiet bearing whine.

 

O.K.. Just was out there playing. As far as I can tell it's a mazda/toyo Kogya M5R2. The ford part sticker is still on it (amazingly) it reads E8TA JD . So you say it uses atf? My previous experience was with a T-18 and I ran gear oil in that. As far as my shifting problems. I took off the boot to see the top of the tranny. The ball the stick is connected to seems to have dropped about a half inch into the housing and there are remnants of a plastic washer? Any ideas?

 

Here's a link with the insides of that trans.

http://www.drivetrain.com/transillm5r1_m5r2.html

Note: There is also a M5r2 that was used on the Thuderbirds. The shifter was on the tail shaft.

Many years ago the dealers carried that black plastic bushing. So if you print out the diagram and take it to the dealer they may stock it. Otherwise search the web.

Also you should look at the back of the shifter cover there are 3 rubber plugs. Those plugs harden over time and the trans fluid would leak. There are some metal plugs that you can purchase to replace the rubber ones.
They are Dorman 555108. You can purchase the plugs from http://www.rockauto.com I believe you have to purcase qty. 10.

If you just want to pull the top cover of the trans., pull the carpet back and you'll see a metal housing that you can unbolt to gain access to the trans. from above. You may have to pull the seat to make it easier.