Dana 18 differences in gears

I am looking at building a hybrid case (D18 gears in a D20 housing) I know I will need the intermediate shaft gear from a 1 1/4 D18, but can I use any of the gears in my 1 1/8 D18? If I could it would save me quite a bit of $$

Which gears are interchangeable.....

 

There is a table of gears with part numbers on the Novak site.

http://www.novak-adapt.com/knowledge/transfer_case_gears_grid.htm

 

You have to use all the gears from either a 26 tooth or 29 tooth transfer case. Don't go by the intermediate shaft size because you can put 26 tooth gears in a 1 1/4" intermediate shaft case or 29 tooth gear set in a 1 1/8" intermediate case and vice verse. I've even seen 20 gears in an 18 case.

 

What's the advantage?

 

I think the D18 has a lower Low Range.

 

That is correct. The D20 only has 2.03 low range while the D18 has a 2.46. I need the centered rear of the D20 for my rear D44 swap