I've driven the same '65 Mustang for more than 20 years. Lately I've had some intermittent problems with it starting, that I think are connected with my automatic transmission--that is it acts like the gear shift isn’t completely in "Park." However, when the problem occurs, it also won't start in "Neutral." I can't be sure this is what the problem is, but after playing with the gear shift a few times, it starts right up.
Ever run across this problem? Any ideas what it could be?
if it has a park and neutral saftey switch then thats what it prolly is... u can bypass these by taking the switch out and splicing the wires together i believe....
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1996 mustang vortech v-2 sq blower with aftercooler 10psi, proffesional products 75mm tb and plenum,bbk long tubes,custom x-pipe,flowmaster cat back,3.73, optima red top in trunk,steeda clutch quadrant and fire wall adjuster,poly motor and trans mounts,alum drive shaft,maxium motorsports suspension,tubular k-member/arms, qa-1 struts and shocks,steeda cc plates,custom subframe connectors,welded torque boxes,t/a rearend cover,walbro255, b&m shifter/triax handle,sct tuner.90mm lighting mam
The problem is either in the shift linkage or with the neutral safety switch itself. Basically, the switch keeps the vehicle from starting in any selection but park or neutral. Check the bushings on your shifer for excess play and make sure the shift handle and linkage are adjusted so the switch aligns with park and neutral. If the linkage is good, then its probably the switch. Bushings and replacement switches are available from many Mustang parts sellers.
1965 Mustang starting problem 
