The only other suggestion is to find a near "sister" boat, one from same yard at same time. Tho be careful! My flawless logic said my U557 should be identical to her sister U558, rather than her other sister U556, it turns out I was wrong! Pix were scarce (non-existent) when I started, but after finishing about 5 popped up showing that 557 was actually more like 552 and 556. Only in a few details, however.