For the D refit challenge I've picked the Grasshopper 5J. How they managed to screw this one up so thoroughly a mere 9 years after they produced the 5N I have no idea, but three changes are enough to undo it.
1. 22 SHS to 14 DHS, use the freed tonnage to install an ER PPC and an extra medium laser.
2. Rip out the Streak launcher and it's ammo, replace with 3 MLs in the same crit spaces.
3. Remove the AMS and it's ammo and stick a pair more MLs where they were.
The result can fire both the ER guns and walk or fire all the MLs while jumping and be heat neutral. Honestly it's one of the "boring energy boats" that some people complain about when talking about customs, but the 5N was that already so I'm not at all guilty for this one:
Grasshopper GHR-6N
Mass: 70 tons
Tech Base: Inner Sphere
Chassis Config: Biped
Rules Level: Tournament Legal
Era: Succession Wars
Tech Rating/Era Availability: E/X-F-D-A
Production Year: 3049
Cost: 6,976,573 C-Bills
Battle Value: 1,775
Chassis: Unknown Standard
Power Plant: Unknown 280 Fusion Engine
Walking Speed: 43.2 km/h
Maximum Speed: 64.8 km/h
Jump Jets: Unknown
Jump Capacity: 120 meters
Armor: Unknown Standard Armor
Armament:
1 ER PPC
1 ER Large Laser
8 Medium Lasers
Manufacturer: Unknown
Primary Factory: Unknown
Communications System: Unknown
Targeting and Tracking System: Unknown
================================================================================
Equipment Type Rating Mass
--------------------------------------------------------------------------------
Internal Structure: Standard 107 points 7.00
Engine: Fusion Engine 280 16.00
Walking MP: 4
Running MP: 6
Jumping MP: 4 Standard
Jump Jet Locations: 2 LL, 2 RL 4.00
Heat Sinks: Double Heat Sink 14(28) 4.00
Heat Sink Locations: 2 LT, 1 RT
Gyro: Standard 3.00
Cockpit: Standard 3.00
Actuators: L: SH+UA+LA+H R: SH+UA+LA+H
Armor: Standard Armor AV - 208 13.00
Internal Armor
Structure Factor
Head 3 9
Center Torso 22 30
Center Torso (rear) 13
L/R Torso 15 20
L/R Torso (rear) 10
L/R Arm 11 22
L/R Leg 15 26
================================================================================
Equipment Location Heat Critical Mass
--------------------------------------------------------------------------------
Medium Laser HD 3 1 1.00
ER Large Laser CT 12 2 5.00
4 Medium Lasers RT 12 4 4.00
ER PPC LT 15 3 7.00
Medium Laser LT 3 1 1.00
Medium Laser RA 3 1 1.00
Medium Laser LA 3 1 1.00
Free Critical Slots: 21
BattleForce Statistics
MV S (+0) M (+2) L (+4) E (+6) Wt. Ov Armor: 7 Points: 18
4j 4 4 1 0 3 2 Structure: 6
Special Abilities: ENE, SRCH, ES, SEAL, SOA
As for the B refit it's a lot tougher, I think everyone will be hard pressed to beat the canon Panther 9K to 9KA "downgrade". My entry is for the Hoplite-4D, which had the opposite problem to the Panther; loads of spare heat sinks.
Remove the LBX AC10 and ammo, replace with an ER PPC and 2 MPLs where the gun was and 2 MLs in place of the ammo. An ER PPC with single heat sinks isn't the best, but if you've already go them you might as well use them. Given another D refit I'd have loved to have added jump-jets to match the Grasshoppers movement profile, but such is life:
Hoplite HOP-4F
Mass: 55 tons
Tech Base: Inner Sphere
Chassis Config: Biped
Rules Level: Tournament Legal
Era: Succession Wars
Tech Rating/Era Availability: E/X-F-D-A
Production Year: 3050
Cost: 4,503,008 C-Bills
Battle Value: 1,240
Chassis: Unknown Standard
Power Plant: Unknown 220 Fusion Engine
Walking Speed: 43.2 km/h
Maximum Speed: 64.8 km/h
Jump Jets: None
Jump Capacity: 0 meters
Armor: Unknown Standard Armor
Armament:
1 ER PPC
2 Medium Pulse Lasers
2 Medium Lasers
1 LRM-5
Manufacturer: Unknown
Primary Factory: Unknown
Communications System: Unknown
Targeting and Tracking System: Unknown
================================================================================
Equipment Type Rating Mass
--------------------------------------------------------------------------------
Internal Structure: Standard 91 points 5.50
Engine: Fusion Engine 220 10.00
Walking MP: 4
Running MP: 6
Jumping MP: 0
Heat Sinks: Single Heat Sink 16 6.00
Heat Sink Locations: 2 LT, 2 RT, 2 LL, 2 RL
Gyro: Standard 3.00
Cockpit: Standard 3.00
Actuators: L: SH+UA R: SH+UA
Armor: Standard Armor AV - 184 11.50
Internal Armor
Structure Factor
Head 3 9
Center Torso 18 26
Center Torso (rear) 9
L/R Torso 13 18
L/R Torso (rear) 8
L/R Arm 9 18
L/R Leg 13 26
================================================================================
Equipment Location Heat Critical Mass
--------------------------------------------------------------------------------
2 Medium Lasers RT 6 2 2.00
ER PPC RA 15 3 7.00
2 Medium Pulse Lasers RA 8 2 4.00
LRM-5 LA 2 1 2.00
@LRM-5 (24) CT - 1 1.00
Free Critical Slots: 34
BattleForce Statistics
MV S (+0) M (+2) L (+4) E (+6) Wt. Ov Armor: 6 Points: 12
4 2 2 1 0 2 2 Structure: 5
Special Abilities: SRCH, ES, SEAL, SOA