I'm rewriting this post because for some reason the site would not post even though I was logged in and it lost the post (with all of the detail info in it). I've scanned through all 10 pages in the forum after a search for the word 'speedometer', but didn't exactly find my answer. This is the short version of my question. What is correct for a '70 1GS455/GSX (with A/C) and TH400, 3.42 gears (assuming G60-15 with a 26.4 tire height)? a 36-39 housing, with a 15 and 39 drive/driven gear set -OR- a 40-45 housing, with a 15 and 40 drive/driven gear set -OR- a 40-45 housing with 17 and 44 drive/driven gear set -OR- a 40-45 housing with 17 and 45 drive/driven gear set Thanks in advance.