Here is Mentzer's Origianl routine outlined in HEAVY DUTY. This is not the HEAVY DUTY from 1993, but the book he wrote in 1978.
Monday / Thursday
Legs
1. Leg Extensions
2. Leg Press 2 Cycles
3. Squat 1 set
4. Leg Curl 1 set
5. Toe Raises 2-3 sets
Chest
1. Dumbbell Fly’s
2. Incline Press 2 cycles
Triceps
1. Triceps Pressdown
2. Dips 2 cycles
Tuesday / Friday
Lats
1. Stiff Arm Pulldown
2. Pulldowns 2 cycles
3. One Arm DB Row 2 sets
Traps
1. Shrugs
2. Upright Rows 2 cycles
Delts
1. Dumbbell Laterals
2. Press Behind Neck 2 cycles
3. Bent Laterals 2 sets
Biceps
1. Barbell Curls
2. Palm Up Chins 2 cycles
Monday / Thursday
Legs
1. Leg Extensions
2. Leg Press 2 Cycles
3. Squat 1 set
4. Leg Curl 1 set
5. Toe Raises 2-3 sets
Chest
1. Dumbbell Fly’s
2. Incline Press 2 cycles
Triceps
1. Triceps Pressdown
2. Dips 2 cycles
Tuesday / Friday
Lats
1. Stiff Arm Pulldown
2. Pulldowns 2 cycles
3. One Arm DB Row 2 sets
Traps
1. Shrugs
2. Upright Rows 2 cycles
Delts
1. Dumbbell Laterals
2. Press Behind Neck 2 cycles
3. Bent Laterals 2 sets
Biceps
1. Barbell Curls
2. Palm Up Chins 2 cycles