Thanks Gordon, I'll get to sending you my preliminary 3-view drawing sometime soon. I'll annotate it with the measurements I want confirmed. The way this came about was, I have a 'gunnadoo' project for a 1/16 RC LVT-1 model one day. I searched the net high and low but couldn't find anyone who had done a LVT-1 scale drawing. I think David Harper (the author of some great LVT books, and an LVT expert) plans to do one sometime, but have no idea when.
On eBay someone regularly auctions copies of 1940s magazine plans for building wooden models, and had an LVT-1 plan in 1/12 scale. Using those I synthesised the CAD drawing that I need checked. By the way the plan instructions mention the track grousers were angled specifically to divert water away from the sides of the vehicle and thus keep the crew and troops drier.
As for the 3-step vs 2-step side, I had a look through my copy of Squadron's 'Amtracs in Action' book. It doesn't mention anything about the dates for the step change. I'm left even more confused because it shows diagrams and photos of the original Roebling 'Alligator 3' with a 3-step pontoon, as well as (all?/some?) of the first batch of 100 built plus second batch of 200 with same. But then the photos show production LVT-1's (1225 made) with a 2-step pontoon. However, it then has a photo of a late-production LVT-1 with a 3-step side! Hmmm beats me.
The early production LVT-1's had widely-spaced front windows but late production ones were close together. Also you'll notice in the TM on page 185 only the very early models had hydraulic tensioners for the track bullnose, this was quickly dropped in favour of the screw-adjustment system - must have been more trouble than it was worth.
That gearbox welding repair looks impressively desperate. Modern engine and heavy equipment rebuild shops could probably tackle that with newer techniques ...if sufficient money was thrown at them.
Steve.