[Blas]

I just did the trans fluid in a 3550. I purchased 3 quarts of Royal Purple (their GM Syncromesh equilvant) and used 2.75 qts. Be carefull which plugs you use to drain and fill. As I remember, the fill is on the passenger side and of course, the drain is on the bottom. Using the wrong fill plug will cause a bad day for you. Fill it till the trans fluid is equal to the fill hole opening with the car level. There are some specialized trans fluids that many people seem to like...Check out www.performanceunlimited.com/cobravalley
for on of the most popular additive. Regarding the engine oil capacity, the usual oil pans call for between 7 and 9 quarts. With the oil cooler and lines add maybe a quart...Isn't the dipstick calibrated? Keep in mind that you don't empty the cooler & their associated oil lines when you change your oil...If you have a Canton pan and a part number, you can get it's capacity...The SCOF owners website has info and hints on changing the trans fluid too. You need to register on the site to access the tech area files. www.performanceunlimited.com/scof/index.html
PM me for more info on SCOF or the trans/oil change...
There is also a important issue to check on the rear suspension...ASAP. It's covered on the above noted website...or once again PM me.