Sorry @Frederic I wrongly compared 1st Gear 4Lo with 1st Gear 4Hi, should be 4th Gear 4Lo (cos my transmission is 4-speed) and 1st Gear 4 Hi., So the new calculation
D. 4Lo Crawl Ratio on 4th Gear 4Lo
= 0.75 4th Gear x 3.12 4Lo x 4.88 front & rear diff = 11.42 on 4th Gear 4Low
E. 4Lo Crawl Ratio on 3rd Gear 4Lo
= 1.00 3rd Gear x 3.12 4Lo x 4.88 front & rear diff = 15.23 on 4th Gear 4Low
Yes you're right, my 3rd Gear 4Lo (point E) will now be similar to my 1st Gear 4Hi (point C) once I upgrade to 10% underdrive gear on the transfer case 😁