I tried to line these up by pinion centerline to demonstrate the extra inch or so of axle tube you get on a front pass drop hybrid axle with the 80. It also shows the extra housing beef overall. The other advantage of the 80 is that it has a built-in speed sensor boss which is useful for EFI engines. Even if you don't have an EFI engine, you can run the signal off that sensor directly to an aftermarket digital speedo to get your speed as you are hauling past all your buddies. 
14-bolt lip.
80 lip.
This pic is deceiving because there is a shock bracket that you can't see on the other side of the 80 housing that is holding the 80 up off the ground 2 - 3 inches. The 14-bolt is sitting flat on the dif cover flange. If the 80 was sitting flat like the 14-bolt the pinion would be 2 - 3" lower.
Left to right: d70hd 4.56, 14-bolt 3.73, d80 5.38. I didn't really want to post this because the differences are so drastic as a result of the different ratios. I would really like to see a 14-bolt 5.38 next to my d80 5.38 but these are all the gears I have for these axles. But it is worth noting the wider / longer teeth on the 80 ring gear as it spreads the load out over a greater surface area than the 70 or the 14-bolt.
Just for shits and giggles, d80 applications up through 1999:
605303 FORD 80 REAR 1988 F-350 SUPER DUTY
605400 FORD 80 REAR 1989 F-350 SUPER DUTY
605445 FORD 80 REAR 1990-91 1/2 F-350 SUPER DUTY
605461 FORD 80 REAR 1992-93 1/2 F-450 CHASSIS-DRW-FULLFLOAT
605499 GM 80 REAR 1992 MOTOR HOME/DISC BRAKES - 80
605524 GM 80 REAR 1992 1/2-93 1/2 GMT 455 - 80
605526 GM 80 REAR 1992 1/2-93 1/2 P-TRUCK - 80
605527 GM 80 REAR 1992 1/2-93 1/2 P-TRUCK - 80
605575 GM 80 REAR 1993-93 1/2 GMT 455 - 80
605592 CHRY 80 REAR 1994-95 1/2 D3500
605593 CHRY 80 REAR 1994-95 1/2 D3500
605594 CHRY 80 REAR 1994-95 1/2 D/W3500
605595 CHRY 80 REAR 1994-95 1/2 D2500
605596 CHRY 80 REAR 1994-95 1/2 W2500
605601 GM 80 REAR 1993-96 1/2 MOTOR HOME/DISC BRAKES - 80
605632 FORD 80 REAR 1993-94 1/2 F-450 CHASSIS-DRW-FULL FLOAT
605638 GM 80 REAR 1994-95 1/2 W2500
605638 GM 80 REAR 1994 1/2-95 1/2 P-TRUCK - 80
605643 GM 80 REAR 1993 1/2-95 1/2 P-TRUCK - 80
605644 GM 80 REAR 1993-95 1/2 P-TRUCK - 80
605649 GM 80 REAR 1995-95 1/2 GMT 455 - 80
605691 GM 80 REAR 1995-95 1/2 GMT 455 - 80
605695 GM 80 REAR 1994 1/2-95 1/2 GMT 455 - 80
605712 GM 80 REAR 1994 1/2-95 1/2 P-TRUCK - 80
605717 FORD 80 REAR 1995-95 1/2 F-450 CHASSIS-DRW-FULL FLOAT
605718 CHRY 80 REAR 1995-97 SWEPTLINE VEHICLE
605719 GM 80 REAR 1995-95 1/2 MOTOR HOME/DISC BRAKES - 80
605745 GM 80 REAR 1994 1/2-95 1/2 P-TRUCK - 80
605753 GM 80 REAR 1995 1/2-95 1/2 GMT 455 - 80
605767 GM 80 REAR 1995-95 1/2 P-TRUCK - 80
605783 GM 80 REAR 1995-95 1/2 P-TRUCK - 80
605788 CHRY 80 REAR 1996-96 1/2 D3500
605789 CHRY 80 REAR 1996-96 1/2 D3500
605790 CHRY 80 REAR 1996-96 1/2 D/W3500
605791 CHRY 80 REAR 1996-96 1/2 D2500
605792 CHRY 80 REAR 1996 1/2 D2500
605807 FORD 80 REAR 1997-98 E-350 DRW CHASSIS - FULL FLOAT
605810 GM 80 REAR 1996-96 1/2 P-TRUCK - 80
605811 GM 80 REAR 1996-96 1/2 P-TRUCK - 80
605812 GM 80 REAR 1996-98 P-TRUCK - 80
605813 GM 80 REAR 1996 1/2 P-TRUCK - 80
605814 GM 80 REAR 1996-98 P-TRUCK - 80
605815 GM 80 REAR 1996-98 P-TRUCK - 80
605816 GM 80 REAR 1996-98 P-TRUCK - 80
605817 GM 80 REAR 1996-96 1/2 P-TRUCK - 80
605818 GM 80 REAR 1996-96 1/2 P-TRUCK - 80
605831 FORD 80 REAR 1996-98 F-450 CHASSIS-DRW-FULL FLOAT
605834 FORD 80 REAR 1996 E-350 DRW CHASSIS - FULL FLOAT
605838 GM 80 REAR 1996 1/2-97 P-TRUCK - 80
605839 GM 80 REAR 1996 1/2-97 P-TRUCK - 80
605840 GM 80 REAR 1996 1/2-97 P-TRUCK - 80
605858 GM 80 REAR 1996 1/2 GMT 455 - 80
605867 GM 80 REAR 1996-99 GMT 455 - 80
605868 GM 80 REAR 1996-98 GMT 455 - 80
605869 GM 80 REAR 1996-98 GMT 455 - 80
605896 GM 80 REAR 1996 1/2-97 P-TRUCK - 80
605902 CHRY 80 REAR 1997 D3500
605903 CHRY 80 REAR 1997 D3500
605904 CHRY 80 REAR 1997 D/W3500
605905 CHRY 80 REAR 1997 D2500
605906 CHRY 80 REAR 1997 D2500
605924 FORD 80 REAR 1998 1/2-99 F-350 CHASSIS-DRW-FULL FLOAT
605925 FORD 80 REAR 1998 1/2-99 F-450 CHASSIS-DRW-FULL FLOAT
605926 FORD 80 REAR 1998 1/2-99 F-350 PICK-UP DRW-FULL FLOAT
605942 FORD 80 REAR 1998 1/2-99 F-350 CHASSIS-DRW-FULL FLOAT
605944 FORD 80 REAR 199 1/2 F-450 MOTOR HOME - DRW - FULL FLOAT
605975 CHRY 80 REAR 1997 1/2 D3500
605976 CHRY 80 REAR 1997 1/2 D3500
605977 CHRY 80 REAR 1997 1/2 D/W3500
605982 CHRY 80 REAR 1998-98 1/2 D3500
605983 CHRY 80 REAR 1998-98 1/2 D3500
605984 CHRY 80 REAR 1998-98 1/2 D/W3500
605985 CHRY 80 REAR 1998-98 1/2 D2500
606040 GM 80 REAR 1997-99 P-TRUCK - 80
606041 GM 80 REAR 1997-99 P-TRUCK - 80
606042 GM 80 REAR 1997-99 P-TRUCK - 80
606043 GM 80 REAR 1997-99 P-TRUCK - 80
606056 CHRY 80 REAR 1997 1/2 W2500
606064 CHRY 80 REAR 1998-98 1/2 W2500
606073 GM 80 REAR 1998 1/2-99 GMT 455 - 80
606074 GM 80 REAR 1998 1/2-99 GMT 455 - 80
606076 FORD 80 REAR 1998 1/2 E-350 SUPER DUTY - DRW - FULL FLOAT
606123 GM 80 REAR 1998 1/2-99 GMT 455 - 80
606144 FORD 80 REAR 1999 E-350 SUPER DUTY - DRW - FULL FLOAT
606201 GM 80 REAR 1999 1/2 P-TRUCK - 80
606202 GM 80 REAR 1999 1/2 P-TRUCK - 80
606203 GM 80 REAR 1999 1/2 P-TRUCK - 80
606204 GM 80 REAR 1999 1/2 P-TRUCK - 80 WIDETRACK
606211 GM 80 REAR 1999 1/2 GMT 455 - 80
606212 GM 80 REAR 1999 1/2 GMT 455 - 80 WIDETRACK
606213 GM 80 REAR 1999 1/2 GMT 455 - 80
606214 GM 80 REAR 1999 1/2 GMT 455 - 80
J. J.
