Don't know about 78 but I changed them on my 74 and it was easy.. Regardless of brand though make sure you get the appropriate shocks for the type driving you do.

Welcome back Tonij. Shocks are so easy a Vega owner could do it. Hardest part is jacking up the car. Put a jack stand under the control arm, directly under the spring, let the car down a little to take the tension off the shock, unbolt the shock, remove it out the bottom. BTW most shocks made today have a 5/16 or 3/8 hex on the upper tip of the shock to hold on while you unbolt the top nut. If your old shocks don't have it, use a vice grip plyers to hold on to the shinny shaft. Reach through the spring to hold with the vice grips. Just remember to not clamp on to the shaft threads. Don't stay gone so long.