Are these gears the same

On the 1st gen rear differentials on these tundras the open diffs that are 43/11 and the lsd diffs that are 44/12 close enough that it will function the same and not mess anything up?

also when I put a new diff in is there a seal I need to buy? Or what seals the diff off

 

You want use same gear ratio front and rear. Differential have a pinion seal behind the yoke and axle seals inboard of the axle flanges.

 

...and a paper gasket between the third member and the housing, although many just use RTV

 

My truck is
*FGR=43:11=3.909 open diff
The diff I’m looking at is
*FGR 44:12 =3.90 lsd diff
Does anyone know the part number for that paper gasket? what’s rtv?

 

rtv = room-temperature-vulcanizing silicone
I use the high temp red/orange on almost everything

 

42181-34011

I recently changed out mine. Faced with the difference between 3.909 and 3.90 I chose to stay with the 3.909 original ratio. Most of the "advice" I found on the Internet said that the difference was insignificant, but I didn't want to take any risk at all.

Beware that the companion flange might be different on your "new" carrier depending on what year/vehicle it was salvaged from.

 

I did this exact swap, below are the ratios stamped into each ring gear.

Open

LSD

Toyota only stamps them to the hundredths decimal place. Send it.