Homemade jerky advice needed

So last night was my first attempt at beef jerky. I used the standard -soy,smoke,worstishire, etc- and i used thinly sliced top round. I then marinated for 24 hours and dried in my oven at 170 for about 8 hours.

It came out delicious and im not looking for marinade advice( though if you have any secret recipes i would be more than willing to critique it :) What i am looking for is advice on how to make it tougher. I want the jerky to be very tough yet dry. The jerky i ended up with was delicious though more on the crunchy side. It still has a little bend to it but something is just off with the texture. I tasted the jerky at different phases and it was always tender. I thought the drier it got, the tougher it would get but that is not the case.

Do i need a different cut of meat? Do i need to leave something out of the marinade? Do i need toslice thicker?

My goal is to immitate loves truck stop jerky in texture but put more flavor into it.

Thanks!