Gelalfett,
Using this resource document
1959 Chevrolet Truck data, your vehicle serial number decodes as:
3E = 3600 (3/4 ton)
59 = 1959 model year
A = Assembled at the Atlanta plant
126962 = your truck was the 26,962nd truck assembled (includes all models) at the Atlanta plant for that year
If you look through the rest of the above linked PDF you will find just about everything you want/need to know about what your truck is. One cautionary word - The vehicle ID plate attached to your cab could have migrated with the 3600 cab to your truck (cab swaps happen all the time). Your 3600 cab could be sitting on a 3100 chassis??? Suggest you may want to do some further reading of this document and compare the rest of your truck (frame/engine/transmission/rear axle) to get a better picture of what you have.
Absolutely come back and ask more questions (in the on topic forums) if you need help figuring out engine, driveline and/or chassis identification.
Dan
