I recommend that you join the Military Vehicle Preservation Assn. (MVPA.org) This will get you two excellent periodical publications one called Army Motors and the other called Supply Line which has advertising from numerous suppliers of replacement parts for MB, GPW and other military vehicles. (See #6 below for suppliers also)
2. Get these books and read them
You should get two books, All - American Wonder Vol. I and Vol. II.
by Ray Cowdery both available through the MVPA
These two books are an excellent restoration guide and reference for a restorer to start out with. There are MANY good books that a restorer should have, but my book, the WWII jeep Guidebook is one that I am obviously partial to ;^) in addition to my book, All-American Wonder I & II are also good ones to start with.
In addition, you should obtain the operators and maintenance manuals for your vehicle (Portrayal Press) to learn how repairs are made, proper operation, and proper maintenance. These manuals can answer many questions. ALL the Military jeep manuals (operations, maintenance & parts) for ALMOST ALL the military jeeps (MB/GPW/M38/M38A1/M151/Hummer) are available on ONE CD for $19.95. This CD is available from www.military-media.com (phone 800-321-2974).
3. Thoroughly check-out the g503.com web site
Go to g503.com and look over the whole site. The links page, production facts, restoration page and message boards, etc., are valuable sources of information.
4. Get yourself set up
a) Camera and notebook for documentation
b) You of course need the basics, a shop with all the typical automotive tools
c) MIG welder (small one - preferably gas shielded instead of flux core type)
d) Angle grinder (invaluable - I have two!)
e) Shop crane (this can be rented)
f) safety equipment (safety glasses, ear protrction, dust masks, fire extinguisher, etc)
g) sandblaster or access to a commercial sandblasting company (this can also be rented as needed)
h) dry storage space for parts, tub, chassis (important!)
i) painting equipment (compressor, etc - this can be rented)
j) understanding and sympathetic spouse!
5. The FIRST order of business
Before you start disassembling your vehicle you must first take the time to document and research it's past. Find the vehicles serial numbers and date of delivery. Some information such as hood registration numbers, unit markings, assembly details, etc. are lost forever by over-ambitious first time restorers who fail to document their vehicle. Photograph it thoroughly in it's "before" state. (You can see some of my documentation pictures at the GPW Image Index.) Note interesting, complex, or unusual details. (Make a sketch of wiring routing details for example.) Find and record the frame number, engine number, body number (MB's) date of delivery info, etc. as all this is needed to make correct decisions later in the process. (Help on how to find these numbers is described in the pages linked to the jeepguy homepage.) Compare what you have found to what is described in the WWII jeep Guidebook, All-American Wonder (AAW), the g503 web site, and the manuals to see what changes occurred to the vehicle over the years. Examine the typical unit marking schemes and carefully remove the paint a layer at a time in those typical locations to try to uncover your vehicle's history. Once you are satisfied that you have documented and researched your vehicle thoroughly, then actual disassembly can begin. I often spend a month or more examining a vehicle before removing anything! Carefully clean - out tool compartments and glove box. I have found important and hard to replace parts in these compartments mixed with trash and debris!
6. Where can I get parts?
Your current issue of Supply Line is your best bet for who has what on sale. Furthermore, the WWII Jeep web site lists many Suppliers with Contact Information. The WWII Jeep web site, maintained by Steven Malikoff, is also an excellent source of information on MB/GPW's. (You may link to it from the Jeepguy Homepage) Another list of suppliers can be found on the g503.com website.