Retro Modern New Rules

( Vehicle means any armoured vehicle )
1) Turret/Hull: If either attack roll die is a "6"  the turret is hit. The suggested counters will have separate Armor Factors for hull and turret.

2) HEAT: If the firer's gun has a HEAT Attack Factor (White , with a "h") the firer may announce "HEAT" before rolling the dice, and use the HEAT Attack Factor instead of the normal (red) Attack Factor.
If "HEAT" is announced, and the defender has a HEAT armour values on the left of the counter (White , with a "h") , use the white HEAT armor values instead of the black values on the left. (This represents special HEAT-resistant armor).

3) Fire Control: The white number on the right is a left shift bonus on the Armor Combat Table, representing rangefinders and computers.

4) Move and Fire: Retro does not allow this, but if you expend 3 movement points or less in the Movement Phase, or change facing, you may fire in the Fire Phase with a penalty. The penalty is a 3-column right shift on the Armor Combat Table. If the counter has a chevron to the left of the tank image, it is a 2-column shift.  If the counter has two chevrons to the left of the tank image, it is a 1-column shift. This represents gun stabilization and computers. No ATGM.

5) Infantry AT Weapons: Just rename the weapons, Panzerfaust -> Disposable LAW, Bazooka->RPG7, allocate regardless of nationality.

6) RCLs: Generic 1960-ish AT support weapons, representing Carl Gustav, SPG-9, M-67 and similar. They use Retro Bazooka rules, but they have double range and use the 12 column of the IFT.
They require 4 portage points (gun + ammo).
Optional: They cannot kill against an armor factor of over 30 (use the HEAT value if there is one) on the vehicle facing hit. Use "Turret/Hull:" rule in Additional Rules.

7) ATGM:  Instead of a huge list of weapons, we go generic. Support Weapon, Max range 60 hex, IFT column 8, Portage 4, and these values:
GenerationMinimum RangeHEAT PenetrationACT column
You use the same Armor Combat Table column for all ranges. Tandem warheads ignore Reactive Armor, Top Attack always hits the side armor. Infantry vehicles firing ATGM are Crew Exposed. You can't fire the gun and the missile in the same turn.
Optional: Accuracy fiends may Google the real weapon stats.  Sagger range 13-75 hex, Milan-1 6-50, TOW-1 2-94. TOW Portage is 6. (3pp no penalty, so 1 square move).  

8) Reactive Armor: If your tank is killed from a front HEAT hit, but you have reactive armor, and the red dice is 1-3, you are saved. Ура!

9) Infantry counters:   A US WW2 10-man squad has probably much the same firepower as a US Bradley 6-man squad. Just play with the WW2 counters.  
Alternatively, you can use the Retro Unit Values Table, but everybody is American. So (6-6-6)  for armoured infantry, and +1 firepower (7-6-6) for truck mounted or static infantry. Every squad would have 2 Panzerfausts (LAW) or a Bazooka (RPG). HMGs still exist, they represent a lot of ammo and spare barrels.  Optionally, every squad has an LMG, no counter needed. SMG squads were largely gone post-Vietnam.
Second rate countries (you decide) get a -1 range  and -1 morale (6-6-6 => 6-5-5) for all units. 
Third rate countries (you decide) get a -2 range  and -2 morale (6-6-6 => 6-4-4) for all units.
Third world peasant armies get an additional -1 firepower due to ancient equipment.

Retro Additional Tank Rules

Counter Art