User Review: JanSport D2
Source: bought it used
Great pack for carrying heavy loads comfortably.
I bought a D3 in 1981 and it was my first large pack. Hiked a bunch with it on the AT. In 1984, I traded a D3 for a D2 that I still have today. The D2 is a great pack.
The D2 and D3 are identical in most respects — same size frame, same size main compartments, same hip belt. The difference is that the D2 was more of a mountaineering pack — instead of 2 side pockets on each side (4 total), it had 1 pocket on each side (2 total) that were sewn on a sleeve that ran the full length of each - skis or wands could fit down the sleeves.
The D2 also had a crampon pouch on the outside of the lower main compartment while the D3 just had a leather pad to strap crampons on and an extra pocket outside the upper main compartment. (Note: the D5 was the version of the D3 for shorter hikers.)
The D2 can carry heavy loads — there were a few times where I had around 70-75 pounds of backpacking and climbing gear in it. Very comfortable pack.
As noted, the only downside is that it is not as good as an internal pack when bushwacking.