There are 3 general type of muffler offsets:

Straight - Straight
Offset - Center
Offset - Offset

Offset/Center
Built for: 96 Dodge Truck Extended Cab With 318 cu in (5.2L)
Unbolt stock Weld on CC Muffler
(May also fit: 96-01 Durango 4 Door 3.9L-4.7L 5.2 L-5.9L)

Offset/Center
Chevy & Ford 4 Door Truck with V/6 Engine
Cut off stock Weld on CC Muffler
Description: Offset ends with 4" 4 Disk CC Inserts
Size: 3" OD - 3 ID Overall length 30½" / 4" Muffler case / 24" long / 3½" Ends

Offset/Center
2003 Dodge Ram Hemi 1500 & 2500 Truck
Description: Offset slotted ends with 4" 4 Disk CC Inserts
Size: 3" ID - 3" ID Overall length 34" / 4" Muffler case 27" long / 3½" Long Ends

Offset/Center
Compact & Import
Description: Offset ends with 3 or 4 Disk 4" CC Inserts
Size: 3" OD - 3" OD Overall length 19" / 4" Muffler case 13" long / 3½" Long ends
Description: Offset ends with 3 or 4 Disk 3½" CC Inserts
Size: 2¼" OD - 2¼" OD Overall length 19" / 3½" Muffler case 13" long / 3½" Long ends

Suburban, Yukon, Tahoe V6
Description: Two Way Inlet and One Way Outlet with 4" 4 Disk CC Inserts
Size: 3" OD 2 1/8" OD Overall Length 28½" / 4" Muffler case 15" long / Inlet End 8½" long

Offset/Offset
86-93 Mustang 5.0L
Offset Ends with 3 Disk 2½" CC Inserts With Factory Location Hanger
Size: 2½" ID - 2½" ID Overall length 19" / 2½" Muffler case 1¾" long ends
Also available with 2¼" ID ends

Offset/Offset
Fit any car with Offset/Offset
Offset Ends with 3 Disk 2½" CC Inserts / No Hanger
Size: 2½" ID - 2½" ID Overall length 19" / 2½" Muffler case 1¾" long ends
Also available with 2¼" ID ends