Have you been here?
p2vneptune.com: In the Beginning, the Vega Model V-135/V-146
p2vneptune.com: Vega Model V-146 (XP2V-1)
The Lockheed P2V Neptune
http://www.history.navy.mil/branches/hist-ac/p2v.pdf
http://www.vpnavy.com/aircraft_p2.html
The P-2V was built in Building 82 at the Lockheed B-6 plant. From I remember talking to some of the old timers who built her, the fuselage came together in 10 segments - The Nose, flight station, NLG bay aft fuselage sections and tail which was either the gun turret or the MAD boom, depending on the model of the -7. The wings were three pieces with the nacelles and QEC built by a subcontractor (I believe it was Rohr Industries of San Diego). Other major subcontractors included Vought, Menasco (Landing Gear) and Emerson (gun turrets).
I'm not quite sure but I think the wings were assembled in a box type jig with the leading edge down. Wing skins were milled planks built up around ribs. The P-3 was similar in construction. Most of the aircraft was 2024 aluminum with some of the major wing attach fittings either 7075 or steel.
I know the P-2 did go together easily. As the segments were built, some of the electrical harnesses were installed and married up in final assembly. Large assemblies I believe were joined with Hi-Locs or a similar high strength fastener. I've never heard anything about the quality, but I do know in the 1950s, Lockheed always had high marks for their quality of construction fo their aircraft, especially those built in Burbank. Sometimes the quality would vary due to attriction or increased production demands that would bring in new people, but for the most part the aircraft always had high marks.
In squadron service the P-2 was easy to maintain compared to other aircraft of its day. The R3350s could be troublesome and like any large round engine, continually leaked oil. I think the 3350s had a TBO of about 1,000 hours when the US Navy operated them.
Inside the aircraft was cramped but had a lot more room than ASW aircraft of WW2. To get to the aft section of the aircraft you had to crawl over the wing box. This area had a smooth cover over it so you jumped on to the box and slid yourself accross it. The Flight Engineer either knelt behind the pilots or had a crude bench that was just a few inches above the floor.
I hope some of this helps - a lot of my comments are based on memory. I worked on P-2s for a very short time; its construction was way before my time. I did build P-3s and also worked on the while serving in the USNR.