I dont want to sound stupid, but do I need a Z?

I have a 90 Ranger XLT, and I have got the cab off, the rear cut off, and ready to start the backhalf. Im going 4.5" trad on the bodydrop adn 20s, but do i need to z my frame, no prob if I do, but does anyone know how much if i do. I cant seem to find it anywhere cept that 98+ need 2" to 2.5" and the pre 98s to 93s lay flat, but have not read anywhere bout beamed rangers. Oh yea, Il take some pics of my progress tomorrow and put of a thread.
THanks in advance
Chris

???

i assume your frame will be level with the bottom of your cab after the body drop...
find the tires your going to run, say its a 225/30/20 which is about 25.3-25.5 inches tall(depending on manufacturer) that puts your spindle center at about 12.7ish inches high... call it 13" for simplicity.
so what you need to determine is when your truck is layed out with the stock frame will your a arms, ibeams or whatever will allow for that much drop so while its layed on the ground jack up your hub and see if it'll go up 13"(thats if your using a 225/30/20. it'll have to go up higher if your using larger tires) if it won't go up to 13" then you'll have to change something, ie Z the frame. say your ibeams will only jack up and get to 10" you'll have to z the frame and raise your suspension section 3". you also have to be sure that you'll be able to untuck your wheels to turn...
remember these are not exact dimensions you should use they are example numbers. you need to find your own actual measurements and plug them in

thanks im usin 255/35R20 wheels/tires. Im gettin drop beams n a week or two, i just gotta wait for this dude to come back to town. I gues Ill just do the back half for now, in then mock up my wheels n beams n then go from there.
Thanks
Chris