The easiest and cheapest thing to do it replace your fluids and filters with a high quality fluids and filters I myself use Amsoil lubes so will recomend those.For the Tranny I would say go with Super Shift Transmission Fluid https://www.amsoil.com/storefront/art.aspx
and for the rear end I would go with a Severe Gear Synthetic Gear Lube https://www.amsoil.com/storefront/svg.aspx
in a 70W90 weight if you have a trac lock then get Slip Loc Differential Addative https://www.amsoil.com/storefront/ada.aspx
.For an air filter I would recomend getting a K&N clean out your carb really really well replace the fuel filter to get some cleaner fuel into the compustion chamber and use a good fuel addative yeah Amsoil,here I will just give you the site copy and paste is killing me AMSOIL Corporate - Source of the World's Best Synthetic Lubricants - Motor Oil and Filters
,makes those to also you can go ahead and switch over to a full synthetic oil as well,my good friend and customer run it in his 67 289 with cork gaskets,and got better mileage and lower operational temps thats why I use full snythetic in all my vehicles it reduces the wear and tear and you get a longer service life.