There are many companies that make a shutdown timer (Greedy, HKS, CATZ, Apexi). I assume all are good products and some are reasonably priced at $85 - $90. If you are not afraid to do a little electrical work under the dash, the install shouldn't be too difficult. IMO pick the one you like the most, as they all have a slightly different look.
If you don't feel comfortable cutting away at wires under the dash, you should try the "Turbo Diesel Life Saver" from Geno's. The cost is a bit higher, but the install in wire splicing/cutting free. Except for the brake wire, if I remember correctlty.
If you don't feel comfortable cutting away at wires under the dash, you should try the "Turbo Diesel Life Saver" from Geno's. The cost is a bit higher, but the install in wire splicing/cutting free. Except for the brake wire, if I remember correctlty.