How difficult is it to replace the head gasket on a Previa?

its not that hard, you just have to have patience and tools

i suggest visiting this website and buying OEM atleast they supply you with diagrams to help guide your way through it
They have all OEM parts to gurantee perfect match, cheap prices, and great customer service.
Head gasket Discount


But out of a scale of 1-10, 10 being the hardest i thinks it a 7-8, all depends on the part and the time you take on the job.

Why do you think you need a head-gasket? Sometimes it could be a head-gasket and other times it ends up being a cracked head (usually between the valves), or worse case scenario, a cracked engine block. Do a compression test both "wet" and dry as well as hooking up a cooling system pressure tester and pumping it up to 16 pounds. If the van will start, then the coolant pressure gauges needle will drop at the dead cylinder. (if you don't have a compression tester).

I Hope This Helps,

~Stillin~