Brake fluid should be dot 3 or dot 4. I think thats all you can buy now. If it happens to be girling approved its dot 4.(that means it can be used with natural rubber parts and wont swell the rubber) You don't have to worry about that thow cause only European cars had natural rubber parts.
Fill it to the top of the master cyl. don"t screw the cap back on tight cause you may have to bleed the system and you will need to refill the reservoir.
If you fill it up and still don't have brake pedal after a couple of pumps then loosen the line at the rear of the master cyl. and bleed it there first. You might get lucky and not have to go to each wheel and bleed the system.
Bleeding will require 2 people one to pump the pedal and one to work the wrench. Try this first;
1. full of fluid, push the pedal to the floor and hold it.
2. loosen the line at the master cyl. --- tighten the line at the master cyl. and let the pedal up.
3. repete 1 and 2.
4. repete 1 and 2.
5. repete 1 and 2.
Do you have a pedal now? Did any fluid come out when you loosened the line? If fluid came out and you don't have pedal go to step 6. If no fluid came out are you sure you loosened the line enough? Try #1 and #2 again this time loosen the line more and shake it side to side.
Try it again. And again. No fluid? Remove the line and put you thumb over the hole. Push the pedal Got a squirt after a couple of trys. Hope so. If not you got a master cyl. problem. Replace it and go to step 6.
Before you start step 6 look at your line routing. On most cars, the furtherest point (by following the brake line to each wheel)from the master cyl. to the wheel cyl. is the rt. rear. On your truck it is the lt. rear wheel.
Step 6 can be done with one person, but you need help the first time. Go get someone who likes you to help.
6. Go to the lt. rear wheel, have you pumper pump the pedal --- oh say 4 times and hold it to the floor. loosen -- WAIT!!-- use a small hammer and some penatrant on the bleeder valve, spray it and give it some lite--- LITE!!! taps straight on the end of the valve. Now re-pump and then loosen the valve (hope it don't brake off)--- tighten the valve and pump it again. Do this till you get nothing but fluid. Then re-fill the reservoir. Go to the rt. rear--- do it the same way. Re-fill, now rt. front, and then lt. front. You should have pedal now. If you don't you got other problems in the system, or just stubborn air bubbles. Good luck.