Dear Wanda,
I also have a E-29 (1976) and just recently pulled my old A4 and installed a new diesel engine, this month. I opted for a diesel for a number of reasons and a new one primarily for reliability.
I purchased a 13hp Beta Marine (Kubota) diesel
and had it professionally installed for under $10,000. I'm very happy with the engine and have only heard positive thing about them. Now, not only don't I worry about having my engine crap out on me, but I also don't worry about stray fuel vapors igniting.
Paul
S/V Bella di Mare