alignment problems

and...what car is this
........did you do the work or did a shop
........ is anything modified from stock

Plymouth Duster 74 slant six

The car came with drum brakes in the front, I switched to disc brakes.

I am in Mexico, the work was done by a mechanic but it is not as formal as in the USA. Next week I'll take him back to the workshop but I want to understand what it could be, the mechanics in Mexico can be very tricky