After speaking with the Mechanic the main mission Sand In The Gas Tank will become available. The 2 side missions are gods and Clowns and Canary In The Coal Mine.
The slave pen is located behind the garage ,so as you leave the garage go around to your left and follow the train tracks, collecting the loot as you go, until you see a set of stairs on your right. At the top of the stairs is a gate that leads into the pen. The key that the mechanic gave you will open the door. Talk to the 2 slaves, Patsy and Not-yet-skinned, at back of the pen, for $10 they’ll give you the gossip on the clowns and the godfishers and the gods and Clowns side mission will be updated. The medic, Stitches, for $200 will only heal you. The merchant ,Whetstone, sells weapons, armour, and ammo.
Back track to the main road and turn right. Across from the garage is an entrance to the arena. Search the arena and collect the loot. The first group of clowns will be at the end of the road. There is an option to talk your way past but I chose not to. There are 6 clowns to deal with. I initiated combat with Simo and took out the flame throwing clown. After that I attacked the clowns that were in range and managed to take them all out except one. The last clown tried to hide in smoke but McBane and Buckshot took him out.
There are 3 slaves trapped by 2 bison off to the left. The bison are not too difficult take out if you keep your distance for as long as you can. After the bison are dealt with talk to the slaves and collect the loot. Behind the slaves there are 2 land mines, an ammo box, a tool box, and a pile of junk.
Thanks for watching, God Bless and happy gaming