got a 98 w/4.2l . Which xmission fluid do I use?

 

Look at your door sticker and find out what transmission you have.

Also pull out your transmission dipstick and see if it has the tranmission fluid type stamped on it...

You can use this link to decode the door sticker...

http://www.fordf150.net/howto/decode.php

 

You have a 4R70W which uses MERCON V.

Older models might specify MERCON/DEXTRON III but you can safely change it to MERCON V if you have it flushed. The MERCON V is better at preventing/fixing converter shudder.

G